Chess
Chess (from Persian shah, king) is a very [1]old two-player board [2]game,
perhaps most famous and popular among all board games in [3]history. In
video game terms we could call it a turn-based strategy, in mathematical
terms it's a [4]zero sum, [5]complete information game with no element of
[6]randomness, that simulates a battle of two armies on an 8x8 board with
different battle pieces, also called chessmen or just men (also stones,
pieces or juicers). Chess is also called the King's Game, it has a
world-wide competitive community and is considered an intellectual
[7]sport but it's also been a topic of research and [8]programming (many
chess engines, [9]AIs and frontends are being actively developed). Chess
is similar to games such [10]shogi ("Japanese chess"), [11]xiangqi
("Chinese chess") and [12]checkers. As the estimated number of chess games
is bigger than [13]googol, it is unlikely to ever be solved; though the
complexity of the game in sheer number of possibilities is astronomical,
among its shogi, go and xiangqi cousins it is actually considered one of
the "simplest" (the board is relatively small and the game tends to
simplify as it goes on as there are no rules to get men back to the game
etc.).
{ There is a nice black and white indie movie called Computer Chess about
chess programmers of the 1980s, it's pretty good, very oldschool, starring
real programmers and chess players, check it out. ~drummyfish }
[14]Drummyfish has created a suckless/[15]LRS chess library
[16]smallchesslib which includes a simple engine called smolchess (and
also a small chess game in [17]SAF with said library).
At [18]LRS we consider chess to be one of the best games for the following
reasons:
* It is just a greatly interesting and deep game in which luck plays
minimal role.
* It is greatly [19]suckless, the rules are very simple, it can be
implemented on simple 8bit computers. Of course the game doesn't even
require a computer, just a board and a few men -- chess masters don't
even need a board to play (they can completely visualize the games in
memory). In the end one can in theory just play against himself in his
head, achieving the ultimate freedom: the only dependency of the game
is one's brain, i.e. it becomes a [20]brain software. Chess is
extremely inexpensive, doesn't discriminate against poor people and
will survive even the most extreme technological [21]collapse.
* No one owns chess, the game is hundreds of years old and many books
about it are also already in the [22]public domain. It is extremely
free.
* It is a basis for other derived games, for example many different
chess variants or chess puzzles which can be considered a
"singleplayer chess game".
* It is a source of many interesting [23]mathematical and programming
challenges.
* It seems to strike the right balance of simplicity and complexity, it
is very simple but not so trivial as to be ever solved in a
foreseeable future.
Many however see [24]go as yet a more [25]beautiful game: a more minimal,
yet more difficult one, with a completely unique experience.
Where to play chess online? There exist many servers such as
https://chess.com or https://chess24.com -- however these ones are
proprietary, so don't use them. For us a possible one is Lichess (libre
chess) at https://lichess.org which not only [26]FOSS, but is also gratis
(it also allows users to run bots under special accounts which is an
amazing way of testing engines against people and other engines), however
it requires JavaScript. Another server, a more [27]suckless one, is Free
Internet Chess Server (FICS) at https://www.freechess.org/ -- on this one
you can play through telnet (telnet freechess.org 5000) or with graphical
clients like pychess. Online servers usually rate players with Elo/Glicko
just like FIDE, sometimes there are computer opponents available, chess
puzzles, variants, analysis tools etc.
Chess as a game is not and cannot be [28]copyrighted, but can chess games
(moves played in a match) be copyrighted? Thankfully there is a pretty
strong consensus and precedence that say this is not the case, even though
[29]capital worshippers try to play the intellectual property card from
time to time (e.g. 2016 tournament organizers tried to stop chess websites
from broadcasting the match moves under "trade secret protection",
unsuccessfully).
Chess and [30]IQ/intelligence: there is a debate about how much of a
weight general vs specialized intelligence, IQ, memory and pure practice
have in becoming good at chess. It's not clear at all, everyone's opinion
differs. A popular formula states that highest achievable Elo = 1000 + 10
* IQ, though its accuracy and validity are of course highly questionable.
All in all this is probably very similar to language learning: obviously
some kind of intelligence/talent is needed to excel, however chess is
extremely similar to any other sport in that putting HUGE amounts of time
and effort into practice (preferably from young age) is what really makes
you good -- without practice even the biggest genius in the world will be
easily beaten by a casual chess amateur, and even a relatively dumb man
can learn chess very well under the right conditions (just like any
dumbass can learn at least one language well); many highest level chess
players admit they sucked at math and hated it. As one starts playing
chess, he seems to more and more discover that it's really all about
studying and practice more than anything else, at least up until the
highest master levels where the genius gives a player the tiny nudge
needed for the win -- at the grandmaster level intelligence seems to start
to matter more. Intelligence is perhaps more of an accelerator of
learning, not any hard limit on what can be achieved, however also just
having fun and liking chess (which may be just given by upbringing etc.)
may have similar accelerating effects on learning. Really the very basics
can be learned by literally ANYONE, then it's just about learning TONS of
concepts and principles (and automatizing them), be it tactical patterns
(forks, pins, double check, discovery checks, sacrifices, smothered mates,
...), good habits, positional principles (pawn structure, king safety,
square control, piece activity, ...), opening theory (this alone takes
many years and can never end), endgame and mating patterns, time
management etcetc.
Fun fact: chess used to be played over [31]telegraph, first such game took
place probably in 1844.
How to play chess with yourself? If you have no computer or humans to play
against, you may try playing against yourself, however playing a single
game against yourself doesn't really work, you know what the opponent is
trying to do -- not that it's not interesting, but it's more of a search
for general strategies in specific situations rather than actually playing
a game. One way around this could be to play many games at once (you can
use multiple boards but also just noting the positions on paper as you
probably won't be able to set up 100 boards); every day you can make one
move in some selected games -- randomize the order and games you play e.g.
with dice rolls. The number of games along with the randomized order
should make it difficult for you to remember what the opponent (you) was
thinking on his turn. Of course you can record the games by noting the
moves, but you may want to cover the moves (in which case you'll have to
be keeping the whole positions noted) until the game is finished, so that
you can't cheat by looking at the game history while playing. If this
method doesn't work for you because you can keep up with all the games, at
least you know got real good at chess :) { This is an idea I just got, I'm
leaving it here as a note, haven't tried it yet. ~drummyfish }
Chess In General
Chess evolved from ancient board games in India (most notably Chaturanga)
in about 6th century -- some sources say that in chess predecessor games
dice was used to determine which man a player was allowed to move but that
once dice were banned because of hazard games, we got the variant without
any element of chance. Nowadays the game is internationally governed by
FIDE which has taken the on role of an authority that defines the official
rules: FIDE rules are considered to be the standard chess rules. FIDE also
organizes tournaments, promotes the game and keeps a list of registered
players whose performance it rates with so called Elo system -- based on
the performance it also grants titles such as Grandmaster (GM, strongest),
Internation Master (IM, second strongest) or Candidate Master (CM). A game
of chess is so interesting in itself that chess is usually not played for
money like many other games ([32]poker, [33]backgammon, ...).
The mastery of chess is often divided into two main areas (it is also
common to divide strong players into these two categories depending on
where their main strength lies):
* positional play: Long term, big picture patterns that offer many
advantages and opportunities for playing good moves, trying to get a
"good position" with men on strong squares, controlling key parts of
the board, putting pressure on enemy, ensuring safety of own king etc.
* tactical play: Short term, quick action, tricks and calculation skills
that win advantages, often material, with tools like forks, pins,
discovery checks, sacrifices etc.
Of course this is not the only possible division, another one may be for
example offensive vs defensive play etc., but generally chess revolves
around position and tactics.
A single game of chess is seen as consisting of three stages: opening
(starting, theoretical "book" moves, developing men), middlegame (seen as
the pure core of the game) and endgame (ending in which only relatively
few men remain on the board). There is no clear border between these
stages and they are sometimes defined differently, however each stage
plays a bit differently and may require different skills and strategies;
for example in the endgame king becomes an active man while in the opening
and middlegame he tries to stay hidden and safe.
The study of chess openings is called opening theory or just theory.
Playing the opening stage is special by being based on memorization of
this theory, i.e. hundreds or even thousands of existing opening lines
that have been studied and analyzed by computers, rather than by
performing mental calculation (logical "thinking ahead" present in
middlegame and endgame). Some see this as weakness of chess that makes
players spend extreme energy on pure memorization. One of the best and
most famous players, Bobby Fischer, was of this opinion and has created a
chess variant with randomized starting position that prevents such
memorization, so called chess 960.
[34]Elo rating is a mathematical system of numerically rating the
performance of players (it is used in many sports, not just chess). Given
two players with Elo rating it is possible to compute the probability of
the game's outcome (e.g. white has 70% chance of winning etc.). The FIDE
set the parameters so that the rating is roughly this: < 1000: beginner,
1000-2000: intermediate, 2000-3000: master. More advanced systems have
also been created, namely the Glicko system.
The rules of chess are quite simple ([35]easy to learn, hard to master)
and can be found anywhere on the Internet. In short, the game is played on
a 8x8 board by two players: one with [36]white men, one with [37]black
(LOL IT'S [38]RACIST :D). Each man has a way of moving and capturing
(eliminating) enemy men, for example bishops move diagonally while pawns
move one square forward and take diagonally. The goal is to checkmate the
opponent's king, i.e. make the king attacked by a man while giving him no
way to escape this attack. There are also lesser known rules that noobs
often miss and ignore, e.g. so called en-passant or the 50 move rule that
declares a draw if there has been no significant move for 50 moves.
At the competitive level clock (so called time control) is used to give
each player a limited time for making moves: with unlimited move time
games would be painfully long and more a test of patience than skill.
Clock can also nicely help balance unequal opponent by giving the stronger
player less time to move. Based on the amount of time to move there exist
several formats, most notably correspondence (slowest, days for a move),
classical (slow, hours per game), rapid (faster, tens of minutes per
game), blitz (fast, a few seconds per move) and bullet (fastest, units of
seconds per move).
Currently the best player in the world is pretty clearly Magnus Carlsen
from Norway with Elo rating 2800+.
During [39]covid chess has experienced a small boom among normies and
[40]YouTube chess channels have gained considerable popularity. This gave
rise to [41]memes such as the bong cloud opening popularized by a top
player and streamer Hikaru Nakamura; the bong cloud is an intentionally
shitty opening that's supposed to taunt the opponent (it's been even
played in serious tournaments lol).
White is generally seen as having a slight advantage over black (just like
in [42]real life lol). It is because he always has the first move --
statistics also seems to support this as white on average wins a little
more often. This doesn't play such as big role in beginner and
intermediate games but starts to become apparent in master games. How big
the advantages is is a matter of ongoing debate, most people are of the
opinion there exists a slight advantage for the white (with imperfect
play, i.e. that white plays easier, tolerates slightly less accurate
play), though most experts think chess is a draw with perfect play (pro
players can usually quite safely play for a draw and secure it if they
don't intend to win; world championships mostly consist of drawn games as
really one player has to make a mistake to allow the other one to win).
Minority of experts think white has theoretical forced win. Probably only
very tiny minority of people think white doesn't have any advantage. Some
people argue black has some advantages over white, as it's true that
sometimes the obligation to make a move may be a disadvantage. Probably no
one thinks black has a forced win, though that's not disproved yet so
maybe someone actually believes it.
On perfect play: as stated, chess is unlikely to be ever solved so it is
unknown if chess is a theoretical forced draw or forced win for white (or
even win for black), however many simplified endgames and some simpler
chess variants have already been solved. Even if chess was ever solved, it
is important to realize one thing: perfect play may be unsuitable for
humans and so even if chess was ever solved, it might have no significant
effect on the game played by humans. Imagine the following: we have a
chess position in which we are deciding between move A and move B. We know
that playing A leads to a very good position in which white has great
advantage and easy play (many obvious good moves), however if black plays
perfectly he can secure a draw here. We also know that if we play B and
then play perfectly for the next 100 moves, we will win with mathematical
certainty, but if we make just one incorrect move during those 100 moves,
we will get to a decisively losing position. While computer will play move
B here because it is sure it can play perfectly, it is probably better to
play A for human because human is very likely to make mistakes (even a
master). For this reason humans may willingly choose to play
mathematically worse moves -- it is because a slightly worse move may lead
to a safer and more comfortable play for a human.
Fun fact: there seem to be almost no black people in [43]chess :D the
strongest one seems to be Pontus Carlsson which rates number 1618 in the
world; even [44]women seem to be much better at chess than black people.
But how about black women? [45]LMAO, it seems like there haven't even been
any black female masters :'D The web is BLURRY on these facts, but there
seems to be a huge excitement about one black female, called Rochelle
Ballantyne, who at nearly 30 years old has been sweating for a decade to
reach the lowest master rank (the one which the nasty oppressive white
boys get at like 10 years old) and MAYBE SHE'LL DO IT, she seems to have
with all her effort and support of the whole Earth overcome the 2000
rating, something that thousands of amateurs on the net just causally do
every day without even trying too much. But of course, it's cause of the
white male oppression =3 lel
Chess And Computers
{ [46]This is an absolutely amazing video about weird chess algorithms :)
~drummyfish }
Chess is a big topic in computer science and programming, computers not
only help people play chess, train their skills, analyze positions and
perform research of games, but they also allow mathematical analysis of
chess as such and provide a platform for things such as [47]artificial
intelligence.
Chess software is usually separated to [48]libraries, chess engines and
[49]frontends. Chess engine is typically a [50]CLI program capable of
playing chess but also doing other things such as evaluating arbitrary
position, hinting best moves, saving and loading games etc. -- commonly
the engine has some kind of custom CLI interface (flags, interactive
commands it understands, ...) plus a support of some standardized text
communication protocol, most notably XBoard (older one, more [51]KISS) and
UCI (newer, more [52]bloated). There is also typically support for
standardized formats such as FEN (way of encoding a chess position as a
text string), PGN (way of encoding games as text strings) etc. Frontends
on the other hand are usually [53]GUI programs (in this case also called
boards) that help people interact with the underlying engine, however
there may also be similar non-GUI programs of this type, e.g. those that
automatically run tournaments of multiple engines.
Computers have already surpassed the best humans in their playing strength
(we can't exactly compute an engine's [54]Elo as it depends on hardware
used, but generally the strongest would rate high above 3000 FIDE). As of
2023 the strongest chess engine is widely agreed to be the [55]FOSS engine
[56]Stockfish, with other strong engines being e.g. Leela Chess Zero (also
FOSS), AlphaZero ([57]proprietary by [58]Google) or Komodo Dragon
(proprietary). [59]GNU Chess is a pretty strong [60]free software engine
by [61]GNU. There are world championships for chess engines such as the
Top Chess Engine Championship or World Computer Chess Championship.
[62]CCRL is a list of chess engines along with their Elo ratings deduced
from tournaments they run. Despite the immense strength of modern engines,
there are still some specific artificial situations in which a human beats
the computer (shown e.g. in [63]this video); this probably won't last long
though.
The first chess computer that beat the world champion (at the time Gary
Kasparov) was famously [64]Deep Blue in 1997. [65]Alan Turing himself has
written a chess playing algorithm but at his time there were no computers
to run it, so he executed it by hand -- nowadays the algorithm has been
implemented on computers (there are bots playing this algorithm e.g. on
lichess).
Playing strength is not the only possible measure of chess engine quality,
of course -- for example there are people who try to make the smallest
chess programs (see [66]countercomplex and [67]golfing). As of 2022 the
leading programmer of smallest chess programs seems to be Óscar Toledo G.
(https://nanochess.org/chess.html). Unfortunately his programs are
[68]proprietary, even though their source code is public. The programs
include Toledo Atomchess (392 [69]x86 instructions), Toledo Nanochess
(world's smallest [70]C chess program, 1257 non-blank C characters) and
Toledo Javascript chess (world's smallest [71]Javascript chess program).
He won the [72]IOCCC. Another small chess program is micro-Max by H. G.
Muller (https://home.hccnet.nl/h.g.muller/max-src2.html, 1433 C
characters, Toledo claims it is weaker than his program). Other engines
try to be strong while imitating human play (making human moves, even
mistakes), most notably Maia which trains several neural networks that
play like different rated human players.
{ Nanochess is actually pretty strong, in my testing it easily beat
[73]smallchesslib Q_Q ~drummyfish }
Programming Chess
NOTE: our [74]smallchesslib/smolchess engine is very simple, educational
and can hopefully serve you as a nice study tool to start with :)
There is also a great online wiki focused on programming chess engines:
https://www.chessprogramming.org.
Programming chess is a [75]fun and enriching experience and is therefore
recommended as a good exercise. There is nothing more satisfying than
writing a custom chess engine and then watching it play on its own.
The core of chess programming is writing the [76]AI. Everything else, i.e.
implementing the rules, communication protocols etc., is pretty
straightforward (but still a good programming exercise). Nevertheless, as
the chess programming wiki stresses, one has to pay a great attention to
eliminating as many [77]bugs as possible; really, the importance of
writing automatic tests can't be stressed enough as debugging the AI will
be hard enough and can become unmanageable with small bugs creeping in.
Though has to go into choosing right [78]data structures so as to allow
nice [79]optimizations, for example board representation plays an
important role (two main approaches are a 64x64 2D array holding each
square's piece vs keeping a list of pieces, each one recording its
position).
The AI itself works traditionally on the following principle: firstly we
implement so called static evaluation function -- a function that takes a
chess position and outputs its evaluation number which says how good the
position is for white vs black (positive number favoring white, negative
black, zero meaning equal, units usually being in pawns, i.e. for example
-3.5 means black has an advantage equivalent to having extra 3 and a half
pawns; to avoid fractions we sometimes use centipawns, i.e. rather -350).
This function considers a number of factors such as total material of both
players, pawn structure, king safety, men mobility and so on.
Traditionally this function has been hand-written, nowadays it is being
replaced by a learned [80]neural network ([81]NNUE) which showed to give
superior results (e.g. Stockfish still offers both options); for starters
you probably want to write a simple evaluation function manually.
Note: if you could make a perfect evaluation function that would
completely accurately state given position's true evaluation (considering
all possible combinations of moves until the end of game), you'd basically
be done right there as your AI could just always make a move that would
lead to position which your evaluation function rated best, which would
lead to perfect play. Though neural networks got a lot closer to this
ideal than we once were, as far as we can foresee ANY evaluation function
will always be just an approximation, an estimation, heuristic, many times
far away from perfect evaluation, so we cannot stop at this. We have to
program yet something more.
So secondly we need to implement a so called search algorithm -- typically
some modification of [82]minimax algorithm, e.g. with alpha-beta pruning
-- that recursively searches the game tree and looks for a move that will
lead to the best result in the future, i.e. to position for which the
evaluation function gives the best value. This basic principle, especially
the search part, can get very complex as there are many possible
weaknesses and optimizations. Note now that this search kind of improves
on the basic static evaluation function by making it [83]dynamic and so
increases its accuracy greatly (of course for the price of CPU time spent
on searching).
Exhaustively searching the tree to great depths is not possible even with
most powerful hardware due to astronomical numbers of possible move
combinations, so the engine has to limit the depth quite greatly and use
various [84]hacks, [85]approximations, [86]heuristics etc.. Normally it
will search all moves to a small depth (e.g. 2 or 3 half moves or plys)
and then extend the search for interesting moves such as exchanges or
checks. Maybe the greatest danger of searching algorithms is so called
horizon effect which has to be addressed somehow (e.g. by detecting quiet
positions, so called quiescence). If not addressed, the horizon effect
will make an engine misevaluate certain moves by stopping the evaluation
at certain depth even if the played out situation would continue and lead
to a vastly different result (imagine e.g. a queen taking a pawn which is
guarded by another pawn; if the engine stops evaluating after the pawn
take, it will think it's a won pawn, when in fact it's a lost queen).
There are also many techniques for reducing the number of searched tree
nodes and speeding up the search, for example pruning methods such as
alpha-beta (which subsequently works best with correctly ordering moves to
search), or transposition tables (remembering already evaluated position
so that they don't have to be evaluated again when encountered by a
different path in the tree).
Alternative approaches: most engines work as described above (search plus
evaluation function) with some minor or bigger modifications. The simplest
possible stupid AI can just make random moves, which will of course be an
extremely weak opponent (though even weaker can be made, but these will
actually require more complex code as to play worse than random moves
requires some understanding and searching for the worst moves) -- one
might perhaps try to just program a few simple rules to make it a bit less
stupid and possibly a simple training opponent for complete beginners: the
AI may for example pick a few "good looking" candidate moves that are
"usually OK" (pushing a pawn, taking a higher value piece, castling, ...)
and aren't a complete insanity, then pick one at random only from those
(this randomness can further be improved and gradually controlled by
scoring the moves somehow and adding a more or less random value from some
range to each score, then picking the moves with highest score). One could
also try to just program in a few generic rules such as: checkmate if you
can, otherwise take an unprotected piece, otherwise protect your own
unprotected piece etc. -- this could produce some beginner level bot.
Another idea might be a "Chinese room" bot that doesn't really understand
chess but has a huge database of games (which it may even be fetching from
some Internet database) and then just looking up what moves good players
make in positions that arise on the board, however a database of all
positions will never exist, so in case the position is not found there has
to be some fallback (e.g. play random move, or somehow find the "most
similar position" and use that, ...). As another approach one may try to
use some non neural network [87]machine learning, for example [88]genetic
programming, to train the evaluation function, which will then be used in
the tree search. Another idea that's being tried (e.g. in the Maia engine)
is pure neural net AI (or another form of machine learning) which doesn't
use any tree search -- not using search at all has long been thought to be
impossible as analyzing a chess position completely statically without any
"looking ahead" is extremely difficult, however new neural networks have
shown to be extremely good at this kind of thing and pure NN AIs can now
play on a master level (a human grandmaster playing ultra bullet is also
just a no-calculation, pure pattern recognition play). Next, [89]Monte
Carlo tree search (MCTS) is an alternative way of searching the game tree
which may even work without any evaluation function: in it one makes many
random playouts (complete games until the end making only random moves)
for each checked move and based on the number of wins/losses/draws in
those playouts statistically a value is assigned to the move -- the idea
is that a move that most often leads to a win is likely the best. Another
Monte Carlo approach may just make random playouts, stop at random depth
and then use normal static evaluation function (horizon effect is a danger
but hopefully its significance should get minimized in the averaging).
However MCTS is pretty tricky to do well. MCTS is used e.g. in Komodo
Dragon, the engine that's currently among the best. Another approach may
lie in somehow using several methods and [90]heuristics to vote on which
move would be best.
Many other aspects come into the AI design such as opening books
(databases of best opening moves), endgame tablebases (precomputed
databases of winning moves in simple endgames), clock management,
pondering (thinking on opponent's move), learning from played games etc.
For details see the above linked chess programming wiki.
Notable Chess Engines/Computers/Entities
See also ratings of computer engines at
https://www.computerchess.org.uk/ccrl/4040/.
Here are some notable chess engines/computers/entities, as of 2024:
* [91]Stockfish (SF): FOSS engine (written in [92]C++), without any
doubt the strongest chess engine that's been reliably winning all the
computer tournaments for years now; its strength is far beyond any
human, even if run on quite a weak device -- it actually caused some
trouble because it's extremely easy to just download onto a cellphone
and [93]cheat even in OTB tournaments. Currently the engine is using a
[94]neural network for evaluating positions but still also uses the
tree search algorithm (a greatly optimized one so that it searches
gigantic numbers of positions per second). Important part of the
development is so called Fishtest, a distributed framework for testing
and improving the engine's performance, it's one of the reasons why it
good so strong. Stockfish's current CCRL Elo rating is 3639 (warning:
this is incomparable to human Elos).
* Magnus Carlsen: Human, most likely the strongest player ever, has been
quite comfortably winning every tournament he entered including the
world championship until he quit, basically because he got "bored".
His top FIDE Elo was 2882.
* Komodo Dragon: [95]Proprietary, currently seems to be the second
strongest engine, it's main feature is [Monte Carlo] ("randomized")
search algorithm. Current CCRL Elo is 3624.
* [96]Leela Chess Zero (lc0): FOSS engine (written in C++), among top
strongest engines (currently top 50 on CCRL), it is interesting mainly
for how it works: it is a neural network engine that's completely
self-taught from the ground up, i.e. it didn't learn chess by watching
anyone else play, it was only allowed to learn by playing against
itself. Current CCRL Elo is 3441.
* [97]Deep Blue: A historically famous supercomputer, the first one to
have beaten the human world chess champion in 1997.
* [98]GNU chess Free engine by [99]GNU, not among absolute top by
strength but still very strong. Current CCRL Elo is 2825.
* Maia: FOSS engine, or rather neural network, notable by not trying to
be the strongest, but rather most human-like, i.e. tries to imitate
human play, even with errors. There are several versions, each trained
for different strength. It is also notable by using pure neural
network, i.e. it doesn't perform any search, it's a pure "pattern
recognition"/static engine that still manages to play quite well.
* Toledo Nanochess: Seems to be the world's smallest [100]C chess
engine, with only 1257 non-blank characters of source code.
* [101]smallchesslib/smolchess: Tiny LRS [102]C library/engine, very
weak but is very simple, small and portable, may be [103]good enough
in many situations.
* Chessmaster: A famous proprietary chess video games with its own
engine, it was strong for a video game of its time (around 2000 Elo)
but nowadays would be considered rather weak for an engine -- its
significance is cultural, it's used for comparisons, many people
played against it and still use it to test their engines against.
* Turochamp: Probably the first chess program ever, made by David
Champernowne and [104]Alan Turing himself in 1948, in times when
computers still couldn't execute it! It was very primitive, looking
only two moves ahead, and was only ever executed manually -- of
course, it got raped pretty bad the human opponent.
* ...
Stats And Records
Chess stats are pretty [105]interesting.
{ Some chess world records are here:
https://timkr.home.xs4all.nl/records/records.htm. ~drummyfish }
Number of possible games is not known exactly, Shannon estimated it at
10^120 (lower bound, known as Shannon number). Number of possible games by
plies played is 20 after 1, 400 after 2, 8902 after 3, 197281 after 4,
4865609 after 5, and 2015099950053364471960 after 15.
Similarly the number of possibly reachable positions (position for which
so called proof game exists) is not known exactly, it is estimated to at
least 10^40 and 10^50 at most. Numbers of possible positions by plies is
20 after 1, 400 after 2, 5362 after 3, 72078 after 4, 822518 after 5, and
726155461002 after 11.
Shortest possible checkmate is by black on ply number 4 (so called fool's
mate). As of 2022 the longest known forced checkmate is in 549 moves -- it
has been discovered when computing the Lomonosov Tablebases.
Average game of chess lasts 40 (full) moves (80 plies). Average
[106]branching factor (number of possible moves at a time) is around 33.
Maximum number of possible moves in a position seems to be 218 (FEN:
R6R/3Q4/1Q4Q1/4Q3/2Q4Q/Q4Q2/pp1Q4/kBNN1KB1 w - - 0 1).
White wins about 38% of games, black wins about 34%, the remaining 28% are
draws (38.7%, 31.1%, 30.3% respectively on Computer Chess Rating Lists).
What is the longest possible game? It depends on the exact rules and
details we set, for example if a 50 move rule applies, a player MAY claim
a draw but also doesn't have to -- but if neither player ever claims a
draw, a game can be played infinitely -- so we have to address details
such as this. Nevertheless the longest possible chess game upon certain
rules has been computed by [107]Tom7 at 17697 half moves in a paper for
[108]SIGBOVIK 2020. Chess programming wiki states 11798 half moves as the
maximum length of a chess game which considers a 50 move rule (1966
publication).
The longest game played in practice is considered to be the one between
Nikolic and Arsovic from 1989, a draw with 269 moves lasting over 20
hours. For a shortest game there have been ones with zero moves; serious
decisive shortest game has occurred multiple times like this: 1.d4 Nf6
2.Bg5 c6 3.e3 Qa5+ (white resigned).
Best players ever: a 2017 paper called Who is the Master? analyzed 20 of
the top players of history based on how good their moves were compared to
Stockfish, the strongest engine. The resulting top 10 was (from best):
Carlsen (born 1990 Norway, peak Elo 2882), Kramnik (born 1975 Russia, peak
Elo 2817), Fischer (born 1943 USA, peak Elo 2785), Kasparov (born 1963
Russia, peak Elo 2851), Anand (born 1969 India, peak Elo 2817), Khalifman,
Smyslov, Petrosian, Karpov, Kasimdzhanov. It also confirmed that the
quality of chess play at top level has been greatly increasing. The best
[109]woman player in history is considered to be Judit Polgar (born 1976
Hungary, peak Elo 2735), which still only managed to reach some 49th place
in the world; by Elo she is followed by Hou Yifan (born 1994 China, peak
Elo 2686) and Koneru Humpy (born 1987 India, peak Elo 2623). Strongest
players of black [110]race (NOT including brown, e.g. India): lol there
don't seem to be many black players in chess :D The first black GM only
appeared in 1999 (!!!) -- Maurice Ashley (born 1966 Jamaica, peak rating
2504) who is also probably the most famous black chess player, though more
because of his commentator skills; Pontus Carlsson (peak Elo 2531) may be
strongest. { Sorry if I'm wrong about the strongest black player, this
information is pretty hard to find as of course you won't find a race
record in any chess player database. So thanks to political correctness we
just can't easily find good black players. ~drummyfish }
What's the most typical game? We can try to construct such a game from a
game database by always picking the most common move in given position.
Using the lichess database at the time of writing, we get the following
incomplete game (the remainder of the game is split between four games, 2
won by white, 1 by black, 1 drawn):
1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 Nf6 5. d4 exd4
6. cxd4 Bb4+ 7. Nc3 Nxe4 8. O-O Bxc3 9. d5 Bf6 10. Re1 Ne7
11. Rxe4 d6 12. Bg5 Bxg5 13. Nxg5 h6 14. Qe2 hxg5
15. Re1 Be6 16. dxe6 f6 17. Re3 c6 18. Rh3 Rxh3
19. gxh3 g6 20. Qf3 Qa5 21. Rd1 Qf5 22. Qb3 O-O-O
23. Qa3 Qc5 24. Qb3 d5 25. Bf1
You can try to derive your own stats, there are huge free game databases
such as the Lichess [111]CC0 database of billions of games from their
server.
{ TODO: Derive stats about the best move, i.e. for example "best move is
usually by queen by three squares" or something like that. Could this
actually help the play somehow? Maybe could be used for move ordering in
alpha-beta. ~drummyfish }
Rules
The exact rules of chess and their scope may depend on situation, this is
just a sum up of rules generally used nowadays.
The start setup of a chessboard is following (lowercase letters are for
black men, uppercase for white men, on a board with colored squares A1 is
black):
_______________
/8 |r n b q k b n r|
r | 7 |p p p p p p p p|
a | 6 |. . . . . . . .|
n | 5 |. . . . . . . .|
k | 4 |. . . . . . . .|
s | 3 |. . . . . . . .|
| 2 |P P P P P P P P|
\1 |R N B Q K B N R|
"""""""""""""""
A B C D E F G H
\_____________/
files
Players take turns in making moves, white always starts. A move consists
of moving one (or in special cases two) of own men from one square to
another, possibly capturing (removing from the board) one opponent's man
-- except for a special en passant move capturing always happens by moving
one man to the square occupied by the opposite color man (which gets
removed). Of course no man can move to a square occupied by another man of
the same color. A move can NOT be skipped. A player wins by giving a
checkmate to the opponent (making his king unable to escape attack) or if
the opponent resigns. If a player is to move but has no valid moves, the
game is a draw, so called stalemate. If neither player has enough men to
give a checkmate, the game is a draw, so called dead position. There are
additional situation in which game can be drawn (threefold repetition of
position, 50 move rule). Players can also agree to a draw. A player may
also be declared a loser if he cheated, if he lost on time in a game with
clock etc.
The individual men and their movement rules are (no man can move beyond
another, except for knight who jumps over other men):
man symbol ~value movement comment
1F, may also 2F from start, promotes on last
pawn P 1 captures 1F1L or 1F1R, also en row
passant
L-shape (2U1L, 2U1R, 2R1U, 2R1D,
knight N 3 2D1R, 2D1L, 2L1U, 2L1D), jumps
over
bishop B 3.25 any distance diagonally stays on same color
sq.
rook R 5 any distance orthogonally (U, R, can reach all sq.
D or L)
queen Q 9 like both bishop and rook strongest piece
king K inf any of 8 neighboring squares
{ Cool players call knights horses or ponies and pawns peasants, rook may
be called a tower and bishop a sniper as he often just sits on the main
diagonal and shoot pieces that wonder through. Also pronounce en passant
as "en peasant". Nakamura just calls all pieces a juicer. ~drummyfish }
Check: If the player's king is attacked, i.e. it is immediately possible
for an enemy men to capture the king, the player is said to be in check. A
player in check has to make such a move as to not be in check after that
move.
A player cannot make a move that would leave him in check!
Castling: If a player hasn't castled yet and his king hasn't been moved
yet and his kingside (queenside) rook hasn't been moved yet and there are
no men between the king and the kingside (queenside) and the king isn't
and wouldn't be in check on his square or any square he will pass through
or land on during castling, short (long) castling can be performed. In
short (long) castling the king moves two squares towards the kingside
(queenside) rook and the rook jumps over the king to the square
immediately on the other side of the king.
Promotion: If a pawn reaches the 1st or 8th rank, it is promoted, i.e. it
has to be switched for either queen, rook, bishop or knight of the same
color.
Checkmate: If a player is in check but cannot make any move to get out of
it, he is checkmated and lost.
En passant: If a pawn moves 2 squares forward (from the start position),
in the immediate next move the opponent can take it with a pawn in the
same way as if it only moved 1 square forward (the only case in which a
men captures another man by landing on an empty square).
Threefold repetition is a rule allowing a player to claim a draw if the
same position (men positions, player's turn, castling rights, en passant
state) occurs three times (not necessarily consecutively). The 50 move
rule allows a player to claim a draw if no pawn has moved and no man has
been captured in last 50 moves (both players making their move counts as a
single move here).
Variants
Besides similar games such as [112]shogi there are many variants of chess,
i.e. slight modifications of rules, foremost worth mentioning is for
example chess 960. The following is a list of some variants:
* antichess ([113]suicide, ...): The goal is to lose all men or get
stalemated, rules are a bit changed, e.g. castling and checks are
removed and taking is forced.
* chess 960 aka Fischer's random: Starting position is randomly modified
by shuffling the non-pawn rows (with these rules: king must be between
rooks, bishops on opposite colors and black/white's positions are
mirrored). The rules are the same with a slight modification to
castling. This was invented by Bobby Fischer to emphasize pure chess
skill as opposed to memorizing the best opening moves, he saw the
opening theory as harmful to chess. Chess 960 is nowadays even
advocated by some to become the "main" version of chess.
* [114]chess boxing: Chess combined with box, players switch between the
two games, one wins either by checkmate or knockout.
* crazyhouse: When a player captures a man, it goes into his reserve.
From the reserve a man can be dropped (as a man of the current
player's color) to an empty square instead of making a normal move.
This is a rule taken from [115]shogi.
* different men: Some variants use different men, e.g. empress (moves
like rook and knight) or amazon (queen/knight).
* duck chess: After each move players place a duck on an empty square,
the duck blocks the square. The duck cannot be left on the same
square, it has to be moved. There are no checks, players win by
capturing the king.
* fog of war: Makes chess an incomplete-information game by allowing
players to only see squares they can immediately move to (this is
similarly to some strategy video games).
* horde chess: Asymmetric starting position: large number of black pawns
vs a white army of traditional men. Rules are slightly modified, e.g.
black can only be defeated by having all pawns captured (there is no
black king).
* [116]infinite chess: Infinite chessboard. { Huge rabbithole with
things like "mate in [117]omega" etc. ~drummyfish }
* minichess: Smaller chessboard, e.g. 4x4, 4x8 etc. Los Alamos chess is
played at 6x6 board without bishops (also no promotion to bishop, no
pawn double step, no en passant, no castling). Some are already solved
(e.g. 3x3).
* more players: E.g. 3 man chess or 4 player chess allow more than two
players to play, some use different boards.
* old chess: The rules of chess itself have been changing over time
(e.g. adding the 50 move rule etc.). The older rule sets can be seen
as variants as well.
* puzzle: For single player, chess positions are presented and the
player has to find the best move or sequence of moves.
* racing kings: The starting position has both players on the same side,
the goal is to get one's king to the other side first.
* different board geometries/topologies: e.g. [118]non-Euclidean
([119]hyperbolic, [120]spherical, [121]torus, ...), hexagonal chess
(had some considerable following) etc.
* 3D chess: [122]3D generalization of chess, possible are also other
dimensions (4D, 5D, ... maybe even 1D?).
* randomly chosen variant: Here a chess variant to be played is chosen
at random before the game, e.g. by dice roll. { This is an idea I got,
not sure if this exists or has a different name. ~drummyfish }
Playing Tips
Some general tips and rules of thumb, mostly for beginners:
* Try to control the center of the board (D4, D5, E4, E5).
* Don't bring the queen out too early, the opponent can harass it and
get ahead in development.
* Learn some universal setup openings or "systems" to play, e.g. London,
King's Indian, the hippo etc.
* Develop your men before attacking, usually knights go out before
bishops, bishops are well placed on the longest diagonals as
"snipers".
* Learn basic tactics, especially forks (attacking two or more men at
once so that one of them cannot escape capture) and pins (attack one
man so that if he moves out of the way he will expose another one to
be captured).
* King safety is extremely important until endgame, castle very early
but not extremely early. In the endgame (with queens out) king joins
the battle as another active man.
* Pawn structure is very important.
* Watch out for back rank checkmates, make an escape square for your
king.
* Rooks want to be on open files, you also want to CONNECT them (have
both guard each other). Also a rook in the opponents second row
(2nd/7th rank) is pretty good.
* Bishops are generally seen a bit more valuable than knights,
especially in pairs -- if you can trade your knight for opponent's
bishop, it's often good. If your opponent has two bishops and you only
have one, you want to trade yours for his so he doesn't have the pair.
A knight pair is also pretty powerful though, especially when the
knights are guarding each other.
* "Knight on a rim is dim" (knights are best placed near the center).
* An extremely strong formation is both rooks and the queen on the same
open file.
* Blocking the opponents man so that it can't move is almost as good as
taking it. And vice versa: you want to activate all your men if
possible.
* Nubs are weak against long range bishops, they can't see them. Place a
bishop to corner on the long diagonal and just snipe the opponent's
material.
* Don't play "hope chess", always suppose your opponent will play the
best move he can.
* If you can achieve something with multiple men, usually it's best to
do it with the weakest one.
* TODO: moar
How To Disrespect Your Opponent And Other Lulz In Chess
see also [123]unsportmanship
WORK IN PROGRESS, pls send me more tips :)
* OTB (over the board) only:
* Turn your knights to face backwards or in another weird way
(always face the opponent's king etc.). Also place the pieces
unevenly on the squares to piss off opponents with OCD and
autism.
* Behave weird, make weird faces, walk extremely far away from the
board and walk in circles (or just get up and stand up directly
behind your opponent in a completely upright position staring
into the distance without moving at all like a robot lol),
constantly sneeze (try to sneeze every time the opponent touches
a piece), make very long unbroken eye contact with the opponent
while smiling as if you know what he's thinking, call the referee
constantly, go to the toilet after every move, pretend to fall
asleep from boredom etc. Overeat on beans before the game so you
fart a lot and always try to fart as loud as possible. Wear nice
clothes but right before the game go sweat to the gym so that you
smell like a pig and distract the opponent with toxic fume. If
you're a [124]wimmin behave sexually, keep grabbing your boobs,
lick your lips and opponent's captured pieces and silently moan
sometimes as if you're having an orgasm, pretend to masturbate
under the table; if your opponent is male he is almost definitely
smarter than you, you gotta use your woman weapons, but it will
probably work easily on the chess virgins.
* In a tournament change play based on opponent's [125]race or sex,
for example play only one opening against white people and
another opening against black people, see if anyone notices the
pattern :D
* Outside tournament take advantage of the fact that you can do
whatever the fuck you want: have one hand constantly on the clock
and play with the other hand (considered rude and often
forbidden), touch and knock over your opponent's pieces, take
back your moves, ... and of course when you're losing,
"accidentally" knock over the whole board and be like "oops,
let's consider it a draw then" :D
* Trash talk the referee.
* Correct the opponent's pronunciation of en passant, insist it's
pronounced "en peasant".
* ...
* online only:
* Be annoying and offensive in chat, if opponent blunders write gg,
spam ez when you win. If he wins say it was a shit game and
accuse him of [126]cheating.
* Constantly ask for takebacks, offer draws, report legit opponents
for cheating and offensive behavior.
* ...
* Play the bongcloud, fool's mate, 1. h3 or similar offensive opening,
especially against a stronger player. Offer a draw after 1st move.
Just play knight F3 and back constantly. Castle manually even if you
don't have to. Play the exact mirror of opponent's moves -- if he
tries to break it then just always try to get back to mirrored
position.
* When losing constantly offer draws, prolong the game AS MUCH AS
POSSIBLE, before the very last move just let the clock run out.
* Repeatedly try to make swastikas on the board, especially against
colored opponents.
* Underpromote pawns e.g. to knights or bishops.
* When playing a noob, don't just mate him but absolutely rape him,
promote all pawns to knights before winning, then say you didn't even
have to try and that he should look into another game as chess is
clearly not his game.
* Look up chess etiquette and do the exact opposite of what it says.
* ...
LRS Chess
{ Has someone already made this tho? Seems like a pretty obvious
simplification to make. ~drummyfish }
Chess is only mildly [127]bloated but what if we try to unbloat it
completely? Here we propose the LRS version of chess. The rule changes
against normal chess are:
* No castling.
* No en passant.
* Promotion is always to queen.
* No checks or checkmates, king is just another man.
* Whoever takes the opponent's king first wins.
* If a player has no available moves, he loses.
* Only a single draw rule: if game doesn't end in 1024 half moves or
fewer, it is a draw. I.e. there are no weird draw rules (50 move,
repetition, ...). Of course players may still agree on draw anytime.
* Random: optionally random variant of LRS chess can be played. Here we
randomly shuffle the white player's back row men in the starting
position and mirror it for black (no weird conditions on men positions
like in chess 960).
See Also
* [128]shogi
* [129]go
* [130]hexapawn
* [131]hex game
* [132]checkers
* [133]advance wars
* [134]backgammon
* [135]Catan
* [136]Deep Blue
* [137]stockfish
* [138]anal bead
Links:
1. old.md
2. game.md
3. history.md
4. zero_sum.md
5. complete_information.md
6. randomness.md
7. sport.md
8. programming.md
9. ai.md
10. shogi.md
11. xiangqi.md
12. checkers.md
13. googol.md
14. drummyfish.md
15. lrs.md
16. smallchesslib.md
17. saf.md
18. lrs.md
19. suckless.md
20. brain_software.md
21. collapse.md
22. public_domain.md
23. math.md
24. go.md
25. beauty.md
26. foss.md
27. suckless.md
28. copyright.md
29. capitalism.md
30. iq.md
31. telegraph.md
32. poker.md
33. backgammon.md
34. elo.md
35. easy_to_learn_hard_to_master.md
36. white.md
37. black.md
38. racism.md
39. covid.md
40. youtube.md
41. meme.md
42. irl.md
43. chess.md
44. woman.md
45. lmao.md
46. https://www.youtube.com/watch?v=DpXy041BIlA
47. ai.md
48. library.md
49. frontend.md
50. cli.md
51. kiss.md
52. bloat.md
53. gui.md
54. elo.md
55. foss.md
56. stockfish.md
57. proprietary.md
58. google.md
59. gnu_chess.md
60. free_software.md
61. gnu.md
62. https://ccrl.chessdom.com/ccrl/4040/
63. https://www.youtube.com/watch?v=R9IZWgArWUE
64. deep_blue.md
65. turing.md
66. countercomplex.md
67. golf.md
68. proprietary.md
69. x86.md
70. c.md
71. javascript.md
72. ioccc.md
73. smallchesslib.md
74. smallchesslib.md
75. fun.md
76. ai.md
77. bug.md
78. data_structure.md
79. optimization.md
80. neural_network.md
81. nnue.md
82. minimax.md
83. dynamic.md
84. hacking.md
85. approximation.md
86. heuristic.md
87. machine_learning.md
88. genetic_programming.md
89. monte_carlo.md
90. heuristic.md
91. stockfish.md
92. cpp.md
93. cheating.md
94. neural_network.md
95. proprietary.md
96. lc0
97. deep_blue.md
98. gnu_chess.md
99. gnu.md
100. c.md
101. smallchesslib.md
102. c.md
103. good_enough.md
104. turing.md
105. interesting.md
106. branching_factor.md
107. tom7.md
108. sigbovik.md
109. woman.md
110. race.md
111. cc0.md
112. shogi.md
113. suicide.md
114. chess_boxing.md
115. shogi.md
116. infinity.md
117. omega.md
118. non_euclidean.md
119. hyperbolic.md
120. spherical.md
121. torus.md
122. 3d.md
123. unsportmanship.md
124. woman.md
125. race.md
126. cheating.md
127. bloat.md
128. shogi.md
129. go.md
130. hexapawn.md
131. hex_game.md
132. checkers.md
133. advance_wars.md
134. backgammon.md
135. catan.md
136. deep_blue.md
137. stockfish.md
138. anal_bead.md