Dijkstra's weakest-precondition calculus turned program semantics into a backward calculation from desired postconditions toward the conditions needed for correct execution.
Edsger Dijkstra's semaphore abstraction gave concurrent programs explicit P and V operations for mutual exclusion, resource counting and process coordination.
Edsger Dijkstra's shortest-path algorithm repeatedly finalizes the nearest reachable vertex, turning weighted-route search into a disciplined greedy process with a provable invariant.
Structured programming reframed program clarity as an engineering property, arguing that control flow should be composed from understandable structures rather than arbitrary jumps.