Greg Strong wrote on Mon, Sep 2, 2019 02:17 PM UTC:
Ok, I've found the issue. It was the result of a recent change. To limit explosion in the size of the search tree by quiescent search, I was only doing four full plies of qsearch after which I was considering recaptures only. The problem is that I didn't have an exception for instances where the king was in check. So if the king couldn't get out of check with a recapture it was scoring the position a mate.
ChessV now agrees that e5f6 is the best move. e5f6 h6g5 f6f7 e8f7 d3e4 c8e6 f1c4 e6c4 b3c4 a8a5
Ok, I've found the issue. It was the result of a recent change. To limit explosion in the size of the search tree by quiescent search, I was only doing four full plies of qsearch after which I was considering recaptures only. The problem is that I didn't have an exception for instances where the king was in check. So if the king couldn't get out of check with a recapture it was scoring the position a mate.
ChessV now agrees that e5f6 is the best move. e5f6 h6g5 f6f7 e8f7 d3e4 c8e6 f1c4 e6c4 b3c4 a8a5