TalkChess.com

[H.G.Muller]

Actually you can put a lot in material tables:

1) Piece interactions (Bishop pair, but also devaluation of Queen-class pieces by presence of opponent minors, devaluation of Pawns when you have a piece minority).
2) Trading gradients (encouraging game-phase progress when you have a winning advantage, say > +2).
3) Flagging special cases (tablebase / bitbase probing, recognizers).

The way I am setting it up now considers light and dark Bishops as different pieces (so the Bishop index runs 0-3 in stead of 0-2), so I can also put discounts on advantages with unlike Bishops. The table contains bytes (and this makes it occupy already 2.6MB, as I have to account for upto 10 Pawns and upto 3 'Queens' for Capablanca), and I plan to assign the highest codes (say 240-255) for special evaluation routines (e.g. indexing a table of functions, or used in a switch statement), and the rest (value-120) as an additive score.

Fruit handles this purely by multipliers: each side gets assigned a multiplier (usually 1) based on the material, and if it is ahead, the advantage is multiplied with it. Multipliers < 1 occur when you have no mating potential in your pieces, and no Pawns, or a single Pawn that the opponent can dispose of by sacrificing a piece.

I am trying to see a pattern in this that could be generalized to other variants, e.g. Spartan Chess. Each code could indicate a routine that sets a certain combination of multipliers other than (1, 1), there are not that many. Or do some special evaluation (e.g. for KPK, KQKP or KBPK).