SAINT
James Slagle's program solved freshman-level indefinite integrals by choosing transformations with heuristics.
Why it matters
Heuristic search first produced a result in a task where human competence is easy to measure by examination.
SAINT solved 84 of the 86 problems in an MIT examination set. The program kept a tree of subgoals and chose a branch by an estimate of difficulty. Slagle was blind and worked with readers. The line continued through SIN and later Macsyma.