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In computational complexity theory and circuit complexity, a Boolean circuit is a mathematical model for combinational digital logic circuits. A formal language can be decided by a family of Boolean circuits, one circuit for each possible input length. Boolean circuits are defined in terms of the logic gates they contain.
A Boolean value is either true or false. A Boolean expression may be composed of a combination of the Boolean constants True/False or Yes/No, Boolean-typed variables, Boolean-valued operators, and Boolean-valued functions. [1] Boolean expressions correspond to propositional formulas in logic and are a special case of Boolean circuits. [2]
In Boolean logic, the majority function (also called the median operator) is the Boolean function that evaluates to false when half or more arguments are false and true otherwise, i.e. the value of the function equals the value of the majority of the inputs.
The above expressions for and can be derived from using a Karnaugh map to simplify the truth table. In this implementation, the final OR gate before the carry-out output may be replaced by an XOR gate without altering the resulting logic.
Example Boolean circuit. The nodes are AND gates, the nodes are OR gates, and the nodes are NOT gates. In theoretical computer science, circuit complexity is a branch of computational complexity theory in which Boolean functions are classified according to the size or depth of the Boolean circuits that compute them.
The XOR is used normally within a basic full adder circuit; the OR is an alternative option (for a carry-lookahead only), which is far simpler in transistor-count terms. For the example provided, the logic for the generate and propagate values are given below. The numeric value determines the signal from the circuit above, starting from 0 on ...
propositional logic, Boolean algebra The statement ¬ A {\displaystyle \lnot A} is true if and only if A is false. A slash placed through another operator is the same as ¬ {\displaystyle \neg } placed in front.
Examples of don't-care terms are the binary values 1010 through 1111 (10 through 15 in decimal) for a function that takes a binary-coded decimal (BCD) value, because a BCD value never takes on such values (so called pseudo-tetrades); in the pictures, the circuit computing the lower left bar of a 7-segment display can be minimized to a b + a c by an appropriate choice of circuit outputs for ...