I rebuilt the 1943 McCulloch-Pitts neuron and checked all 256 three-input Boolean functions. Every one fit in a two-layer net with at most four hidden units.

Part 86 of Forgotten Theories, a series re-testing old scientific claims with modern tools. Find the rest under the #forgotten-theories tag. In 1943 Warren McCulloch, a neuropsychiatrist with a taste for logic, and Walter Pitts, a teenage runaway wh...