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Parity only depends on the number of ones and is therefore a symmetric Boolean function.. The n-variable parity function and its negation are the only Boolean functions for which all disjunctive normal forms have the maximal number of 2 n − 1 monomials of length n and all conjunctive normal forms have the maximal number of 2 n − 1 clauses of length n.
The size of a circuit is the number of gates it contains and its depth is the maximal length of a path from an input gate to the output gate. There are two major notions of circuit complexity. [1] The circuit-size complexity of a Boolean function is the minimal size of any circuit computing .
In 1984 Furst, Saxe, and Sipser showed that calculating the parity of the input bits (unlike the aforementioned addition/subtraction problems above which had two inputs) cannot be decided by any AC 0 circuits, even with non-uniformity. [5] [1] It follows that AC 0 is not equal to NC 1, because a family of circuits in the latter class can ...
The comparator circuit value problem (CCVP) is the problem of evaluating a comparator circuit given an encoding of the circuit and the input to the circuit. The complexity class CC is defined as the class of problems logspace reducible to CCVP. [1] An equivalent definition [2] is the class of problems AC 0 reducible to CCVP.
Comparators are closely related to operational amplifiers, but a comparator is designed to operate with positive feedback and with its output saturated at one power rail or the other. If necessary, an op-amp can be pressed into service as a poorly performing comparator, but its slew rate will be impaired.
In most cases a comparator is implemented using a dedicated comparator IC, but op-amps may be used as an alternative. Comparator diagrams and op-amp diagrams use the same symbols. A simple comparator circuit made using an op-amp without feedback simply heavily amplifies the voltage difference between Vin and VREF and outputs the result as Vout.
TC 0 is a complexity class used in circuit complexity. It is the first class in the hierarchy of TC classes. TC 0 contains all languages which are decided by Boolean circuits with constant depth and polynomial size, containing only unbounded fan-in AND gates , OR gates , NOT gates , and majority gates .
By Lemma 1, we get a branching program for A outputting the identity or α, i.e. α-computing ¬A=C. If the circuit C outputs A∧B for circuits A and B, join the branching programs that γ-compute A, δ-compute B, γ −1-compute A, and δ −1-compute B for a choice of 5-cycles γ and δ such that their commutator ε=γδγ −1 δ −1 is ...