Implement insufficient mating material for Knightmate

KBK is draw with Royal Knight. With exo-pieces also KNK and KFK.

diff --git a/backend.c b/backend.c
index 6e24b1a..92c741c 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -7614,6 +7614,9 @@ MatingPotential (int pCnt[], int side, int nMine, int nHis, int stale, int bisCo
                        || majors + (12*pCnt[BlackFerz-side] | 6*pCnt[BlackAlfil-side]) > 16; // KCKAA, KCKAX, KCKEEX, KCKEXX (XX!=HH), KCKXXX
                // TO DO: cases wih an unpromoted f-Pawn acting as platform for an opponent Cannon
 
+       } else if(v == VariantKnightmate) {
+               if(nMine == 1) return FALSE;
+               if(nMine == 2 && nHis == 1 && pCnt[WhiteBishop+side] + pCnt[WhiteFerz+side] + pCnt[WhiteKnight+side]) return FALSE; // KBK is only draw
        } else if(pCnt[WhiteKing] == 1 && pCnt[BlackKing] == 1) { // other variants with orthodox Kings
                int nBishops = pCnt[WhiteBishop+side] + pCnt[WhiteFerz+side];