(called <em>halfmoves</em> or <em>plies</em>), there are too many unfinished games to keep track of, and the tree of possibilities keeps growing exponentially for 70 or so more plies. The search needs to find a good place to cut things short and make what is called a <em>static evaluation</em>.</p>
        <p>Classical engines assume that both players will always alternate making the best move, so they expand the tree as far as they can then make static evaluations at the leaves, before deciding which line 