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Chess engine: Mida 2.2

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This project is a chess engine called "Mida" built entirely in C++. The engine is built to work with UCI (Universal Chess Interface), and you can easily find all the commands online.

Rating CEDR=3006

v2.2:
This release comes with lots of new features:
Changed History heuristic (now aligned with the implementation of all top engines). This improves the move ordering. Also, history score is now used in LMR to adjust the reduction.

"Improving cuts": We check if the evaluation has improved compared to the eval from the second last node, and if the score is lower, (meaning the branch is not improving), we can search it with more aggressive prunings (for now only in LMP) because it's probably not a good branch.

Increased reduction in Null Move Pruning: the reduction is now adjusted also based on the distance of the eval from beta. Also, null move pruning is now applied only if the eval is >= than beta.

Changes in LMR: the reduction factor (from now will be called R) is now not only the value from the LMR table, but is also adjusted based on the move. In particular:

we reduce R by 2 if the move is a killer move.
We reduce R by a factor history / 4000, where history is the history score for the move
We increase R by 1 if the nod is a non-pv node
We increase R by 1 if we are not improving
We increase R by 1 if the move is quiet
Hash table size set to a default value of 64 MB (still have to make it customizable)

Optimizations in tt entry's size (previouslt 24 bytes, now 16) and added Aging as overwriting condition.

Mida 2.2 download


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