Programming a Computer for Playing Chess
Claude E. Shannon · 1950 · Philosophical Magazine, 41(4), 256–275
Summary
Lays out how a machine might play chess: represent positions, generate legal moves, search the game tree with minimax, and evaluate non-terminal positions with a heuristic scoring function.
Why it matters
It set the template that game-playing programs followed for half a century. The key practical insight, that exhaustive search is impossible so search must be cut off at a depth and the resulting position scored heuristically, is still how game-tree search is structured.