An Immortal Chess Move

Analyze chess positions from the immortal game between Wei Yi and Bruzon Batista

In 2015 Wei Yi and Bruzon Batista played a chess game that has become very famous. It involved a rook sacrifice by Wei Yi followed by a king hunt dragging Bruzon's king further into the danger zone with multiple sacrifices. The key position will be analyzed using functions and the very strong built-in chess engine Arasan from the Wolfram Chess paclet.

Install the Wolfram Chess paclet:

In[1]:=

PacletInstall["Wolfram/Chess"]

Load the paclet:

In[2]:=

Needs["Wolfram`Chess`"]

Here is the FEN of the key position:

In[3]:=

fen1="3qr1k1/1b1rbp2/p2p2p1/1p1np3/4P3/P2BB2Q/1PP3PP/4RR1K w - - 0 22";

This displays the corresponding position using Chessboard:

In[4]:=

Chessboard[fen1]["Graphics","SquareColors"{LightCyan,Darker@Cyan},ImageSize360]

Out[4]=

This uses EngineEvaluate, which calls the Arasan chess engine to find the move f1f7 made by Wei Yi, sacrificing a rook for a pawn, and gives a score indicating that after that move, Wei Yi was a queen ahead—a queen usually being valued at 9 points:

In[5]:=

With[{eval=EngineEvaluate[fen1,"MaxDepth"26]},eval[#]&/@{"Best move","Score"}]

Out[5]=

{f1f7,9.33}

This displays Wei Yi's famous move:

In[6]:=

Chessboard[fen1]["Graphics","SquareColors"{LightCyan,Darker@Cyan},ImageSize360,"Arrows"{"Rf1f7"},"HighlightSquares"{{Opacity[0.7,Red],Annulus[0.5+#,{0.42,0.5}]}&{"f1","f7"}}]

Out[6]=

After 25 moves for each side this position was reached:

In[7]:=

Chessboard[fen2="3qr3/1b1rb2Q/p2p2p1/1p2p3/4k3/P3B3/1PP3PP/4R2K w - - 0 26"]["Graphics","SquareColors"{LightCyan,Darker@Cyan},ImageSize360]

Out[7]=

Wei Yi made the move h7f7 leading to this position:

In[8]:=

Chessboard[fen3="3qr3/1b1rbQ2/p2p2p1/1p2p3/4k3/P3B3/1PP3PP/4R2K b - - 1 26"]["Graphics","SquareColors"{LightCyan,Darker@Cyan},ImageSize360]

Out[8]=

Even searching to a maximum depth of 30, the engine does not see a forced checkmate in that position, but Wei Yi was getting closer to checkmate:

In[9]:=

EngineEvaluate[fen3,"MaxDepth"30]["Score"]

Out[9]=

14.71

However, the engine finds that instead of making the move h7f7, c2c4 leads a forced checkmate in 9 white moves:

In[10]:=

eval2=EngineEvaluate[fen2];eval2[#]&/@{"Best move","DistanceToMate"}

Out[10]=

{c2c4,9}

Define a function to give the list of generated fens from a starting fen and a move sequence:

In[11]:=

FensCorrespondingToAMoveSequence[f_,ms_]:=Module[{b=Wolfram`Chess`MLE`ChessBoard`NewBoard[f]},b@Wolfram`Chess`MLE`ChessBoard`playMoves[b@Wolfram`Chess`MLE`ChessBoard`convertMoves[ms,"SAN","UCI"]]]

This generates the sequence of fens for the moves leading to checkmate:

In[12]:=

Short[fens=FensCorrespondingToAMoveSequence[fen2,eval2["Line"]],5]

Out[12]//Short=

{3qr3/1b1rb2Q/p2p2p1/1p2p3/4k3/P3B3/1PP3PP/4R2K w - - 0 26,3qr3/1b1rb2Q/p2p2p1/1p2p3/2P1k3/P3B3/1P4PP/4R2K b - c3 0 26,3qr3/1b1rb2Q/p2p2p1/1p2p3/2P5/P2kB3/1P4PP/4R2K w - - 1 27,13,4r3/3rb3/pq1p4/4p3/1PQ5/k3B3/3R2PP/7K w - - 1 34,4r3/3rb3/pq1p4/4p3/1PQ5/k3B3/R5PP/7K b - - 2 34}

Here is the chess board corresponding to the move c2c4:

In[13]:=

Chessboard[fens〚2〛]["Graphics","SquareColors"{LightCyan,Darker@Cyan},ImageSize360]

Out[13]=

This displays the position with checkmate found by the chess engine:

Visualize the moves found by the engine leading to checkmate as an animation:

Evaluate the code below to generate an animation of the entire game:

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Contributed by: Jay Warendorff

Wolfram Language Example Repository

An Immortal Chess Move

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