Principal Variation

Principal Variation The principal variation is the sequence of moves that the engine considers best for both sides from the current position. It’s the “main line” — the path through the game tree that alpha-beta search identifies as optimal. When is Principal Variation Used? After search is complete: The PV is the best line the engine found. This is what gets printed to the GUI — “at depth 12, best line is e4 e5 Nf3…”. Totally useful even without ID, just for knowing the answer. ...