Logical machine

The principal examples of such machines are those of William Stanley Jevons (logic piano),[1][2] John Venn,[3] and Allan Marquand.

In the 21st century, these proof assistant programs have given birth to a new field of study called mathematical knowledge management.

The earliest logical machines were mechanical constructs built in the late 19th century.

[6] In 1883, Allan Marquand invented a new logical machine that performed the same operations as Jevons' logic piano but with improvements in design simplification, portability, and input-output controls.

In the abacus the combinations are inscribed each on a single slip of wood or similar substance, which is moved by a key; incompatible combinations can thus be mechanically removed at will, in accordance with any given series of premises.