Some of the possible breakthroughs in electronic hardware discussed below will be directly applicable to the chess issue. For many, such as myself, it will simply be the passing of a long anticipated milestone. While level-3 intelligence will certainly benefit from the increasing power of computer hardware, it will also require substantial improvements in the ability of computers to manipulate abstract concepts. Defenders of human chess playing often say that though computers may eventually defeat all human players, computers are not able to use the more abstract and intuitive methods that humans use. For example, people can eliminate from consideration certain pieces that obviously have no bearing on the current strategic situation and thus do not need to consider sequences of moves involving those pieces.
Humans are also able to draw upon a wealth of experience of previous similar situations.
However, neither of these abilities is inconsistent with the recursive algorithm. The ability to eliminate from consideration branches of the expanding tree of move-countermove possibilities not worth pursuing is an important part, called pruning, of any minimax program. While impressive, it is clear that this is again an area where machines have a distinct edge. Moreover, it is feasible for computers to modify such previously stored board positions to use them even if they do not precisely match a current position. It may very well be that human players deploy methods of abstraction other than recalling previous board positions, pruning and move expansion.