Hello chess lovers. Here is a chess puzzle by Gioachino Greco. This was created in 1623 and its black to move and draw the game. Let’s first turn on the engine Komodo 10 infinite analyzes and then I will speak about this puzzle and also will try to answer the question why are chess engines unable to solve this? You can see that the engine is evaluating the position incorrectly. First of all who was Greco? He was an Italian chess player and writer. He recorded some of the earliest chess games known. His games, all against anonymous opponents (“NN”), were quite possibly constructs but served as highly useful tools for spotting opening traps. Mikhail Botvinnik considered Greco to be the first professional chess player. So why are chess engines unable to find the solution of this puzzle?
Chess engines are just brute forces which in a second are analyzing hundreds of millions of positions. The evaluation engine , assigns a positive (good) or a negative (bad) value to any chess board position. And accordingly the engine is programmed that “if this position occurs, do this or that.Otherwise they are stupid but hardworking machines. I call them stupid because they even analyze a millions of silly moves which a normal chess player won’t even consider. So it all depends how far they can calculate. When it comes to tactics they are perfect. But when speaking about positional chess or endgames, alone with the calculating depth it is difficult to find a correct evaluation. So engines must have Endgame Tablebases, in order to solve such puzzles. Endgame more tricky endgames. Tablebases are precalculated databases that hold for every possible position in a certain endgame, whether it is drawn or how many moves are left for a side to win or lose assuming perfect play. With the help of those, chess engines can simply lookup, if it is advisable to do a certain exchange or not, as well as how to finish some of the more tricky endgames. Such Tablebases are available for all positions containing three to six pieces (counting the kings) and for some seven-piece combinations. The only disadvantage is that, Tablebases are very space consuming and the disk-access tends to be slow. Now what about this puzzle? Did you solve it? As for the engine it can’t see the solution. You can see here are the suggested moves; Ra1. That is true. But after Rf1 it is not calculating to take on f1 but the correct move is taking on f1 Kf1 and now a very difficult choice for black Bh3. Your are taking on h3 and this is a drawn endgame because this bishop is useless because it is of an opposite color of h8 square that’s why this is theoretically drawn position and these pawns are also useless. By the way this Bh3 sacrifice reminds me of Alexey Shirovs move against Veselin Topalov. One day we will cover that endgame as well. But why the computer can’t see or solve this puzzle? To understand which moves are good and which ones are bad you have to know about evaluation function. This function gives the following values to each pieces. Pawn 100, Bishop and knight 300. Rook 500 queen 900 king 100 000 The king must have a much greater value in order not to get sacrificed by the program. So the program won’t give up 300 value because it is unable to calculate up to the end. When the maneuvering in an ending to achieve an irreversible improvement takes more moves than the horizon of calculation of a chess engine, an engine is not guaranteed to find the best move without the use of an endgame Tablebase, and in many cases can fall foul of the fifty-move rule as a result.That’s why the engine chooses another line where it keeps it’s valuable pieces. So what are the conclusions. The engines can only solve this puzzle if they have an endgame Tablebase containing not only positions but also rules. You can see that even in this position after playing Bh3 the engine thinks that white is winning! This much, what other puzzles do you know that computer choke on it. Tell me about it please I will publish them with great pleasure. Good luck.