From: H.G.Muller <hgm@hgm-xboard.(none)>
Date: Mon, 2 Jun 2014 17:55:02 +0000 (+0200)
Subject: Fix tsume condition when both K and CP present
X-Git-Url: http://winboard.nl/cgi-bin?p=hachu.git;a=commitdiff_plain;h=25f905105a3da8d8be0908c40f46f1119dd2ef06

Fix tsume condition when both K and CP present

A position where the side-to-be-mated has both K and CP is never
a check, and should thus not be allowed to occur in a tsume problem.
This was not properly detected. (Strictly speaking it can be a check
if both can be captured on the same move by a Lion/Falcon/Eagle,
but for now we ignore that.)
---

diff --git a/hachu.c b/hachu.c
index 9b98aa7..ffde08b 100644
--- a/hachu.c
+++ b/hachu.c
@@ -1796,7 +1796,12 @@ if(PATH) /*pboard(board),pmap(attacks, BLACK),*/printf("search(%d) {%d,%d} eval=
     if( k == ABSENT) {
       if((k = p[king + 2].pos) == ABSENT && (!tsume || tsume & stm+1))
         return -INF;   // lose when no King (in tsume only for side to be mated)
-    } else if(p[king + 2].pos != ABSENT) k = ABSENT; // two kings is no king...
+    } else if(p[king + 2].pos != ABSENT) {
+      if(tsume && tsume & stm+1) {
+	retDep = 60; return INF; // we win when not in check
+      }
+      k = ABSENT; // two kings is no king...
+    }
     if( k != ABSENT) { // check is possible
       if(!attacks[2*k + xstm]) {
 	if(tsume && tsume & stm+1) {