 Intractability and the combinatorial explosion . In 1972 Richard Karp ( building on Stephen Cook 's 1971 theorem ) showed there are many problems that can probably only be solved in exponential time ( in the size of the inputs ) . Finding optimal solutions to these problems requires unimaginable amounts of computer time except when the problems are trivial . This almost certainly meant that many of the " toy " solutions used by AI would probably never scale up into useful systems . 
 Intractability and the combinatorial explosion . In 1972 Richard Karp ( building on Stephen Cook <a href='null_genetive' title='1'><mark>'s</mark></a>1971 theorem ) showed <a href='dey_it' title='2'><mark>there</mark></a> are many problems <a href='null_relcl' title='3'><mark>that</mark></a>can probably only be solved in exponential time ( in the size of the inputs ) . Finding optimal solutions to these problems <a href='uninflect' title='4'><mark>requires</mark></a> unimaginable amounts of computer time except when the problems are trivial . This almost certainly meant that many of the " toy " solutions used by AI would probably never scale up into useful systems . 
Intractability and da combinatorial explosion . In 1972 Richard Karp ( building on Stephen Cook  1971 theorem ) showed it is many problems can probably only b solved in exponential time ( in tdasize of thdanputs ) . Finding optimal solutions to these problems require unimaginable amounts of computer time except when thedaoblems r trivial . This almost certainly ment dat many of the daoy " solutions used by AI would probably never scale up into useful systems .