Shannon expansion

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The Shannon expansion develops the idea that Boolean functions can be reduced by means of the identity:

F = x * Fx + x' * Fx',

where F is any function and Fxand Fx' are positive and negative Shannon cofactors of F, respectively. It is named for Claude Shannon.

A positive Shannon cofactor of function F with respect to variable x is defined as that function with all x's set to 1. A negative Shannon cofactor is the same, but sets all x's to 0.

The Shannon expansion theorem is an important idea in Boolean algebra. It paved the way for Binary decision diagrams, Satisfiability solvers, and many other techniques relevant for computer engineering and formal verification of digital circuits.


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