Ceibo 0.8

[federicorojo]

Hi All,

It has not been long ago since I released version 0.7, so normally I wouldn't release a new version so soon. However, while working on improving move ordering by applying static exchange evaluation on captures, I accidentaly found a Major bug related to moves from my Transposition Tables worth about +40 Elo. After finding that, I decided to look more closely into my many years old code related to transpositions and voila! found another issue related to en passants worth another +5 to +10. That said, half of the improvement of this version is related to bug fixes, and adding the improvements overall merits the release of a new version.

Changes:

• Move Ordering
  • Static Exchange Evaluation (SEE): applied to captures only for now.
  • Other minor changes

• Search
  • Qsearch: SEE Pruning
  • Internal Iterative Reductions
  • Fixed Futility Pruning issue

• Transposition Tables
  • Fixed Major move ordering issue
  • Fixed Minor en passant issue
  • 4 buckets per entry

• Evaluation:
  • semi and open file rook
  • isolated pawn
  • enhancements to mobility

You may find the latest version in the Dowloads section:
https://sites.google.com/site/ceibochess/downloads


Thanks, Fede

[JimmyRustles]

Could you explain what internal iterative reductions are? I've never heard of it on the wiki or in other engines.

[Gabor Szots]

Thanks Fede. As far as I know Sergio is already testing it.

[federicorojo]

Could you explain what internal iterative reductions are? I've never heard of it on the wiki or in other engines.

It's Ed's idea, as a alternative to Internal Iterative Deepening (IID).

IID never worked for Ceibo, but IIR gave it a few Elo. Pls see his post in CC: http://talkchess.com/forum3/viewtopic.p ... ve#p855898

[federicorojo]

Thanks Fede. As far as I know Sergio is already testing it.

Awesome! Thanks Gabor and Sergio