return alpha;
// Transposition table lookup. At PV nodes, we don't use the TT for
- // pruning, but only for move ordering.
+ // pruning, but only for move ordering. This is to avoid problems in
+ // the following areas:
+ //
+ // * Repetition draw detection
+ // * Fifty move rule detection
+ // * Searching for a mate
+ // * Printing of full PV line
+ //
tte = TT.retrieve(pos.get_key());
ttMove = (tte ? tte->move() : MOVE_NONE);