Search arXivSearch

arXiv · 1309.0029

A Canonical Partition of the Primes of Logic Functions

Abstract

This paper presents algorithms that relate to the problem of finding a minimum-cost sum-of-primes representation of a Boolean function f when the cost function C is positive and additive. A set of primes whose sum equals f is called a basis for f, so a solution to the problem is a minimum-cost basis. The algorithms construct the following canonical partition of the complete set of primes and identify the members of sets 1, 2, and 3: (1) Essential Primes, which must be part of any basis for f, (2) Unnecessary Primes that cannot be part of a minimum-cost basis for f for any positive additive cost function, (3) Unique disjoint sets of primes, PS1,...,PSN with associated "covering" tables TS1,..., TSN such that any minimum-cost basis consists of the union of the sets Essential Primes, QS1(C), ..., QSN(C) where QSi(C) is contained in PSi and QSi(C) is a minimum-cost "cover" for PSi. Covering is defined by operation Cascade(QS, TS), which has the property that QS covers PS if and only if Cascade(QS, TS) is empty. The key to the results is the study of objects called Ancestor Sets. The Ancestor Theorem proves that if A is an Ancestor Set for f, every minimum-cost basis includes a minimum-cost cover for the set of primes PS in Ancestor Set A and a minimum-cost cover for the set of primes that are not in A (and are not covered by the the union of the Essentials with PS). The PSi in the partition are the sets of primes in canonical disjoint Independent Ancestor Sets Ai, which are easy to generate when the calculation of the primes (and their consensus combinations) is within computational scope. The paper also presents a condition under which QSi(C) can be easily determined, and another condition such that PSi can be broken into disjoint pieces that can be minimized separately.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Sidnie Feit. 2014-07-31. A Canonical Partition of the Primes of Logic Functions. https://arxiv.org/abs/1309.0029

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

Adjunctions, Box Products, and Forcing Families

Sidorenko's conjecture states that the number of copies of any given bipartite graph in another graph of given density is asymptotically minimized by a random graph. For bipartite graphs containing a cycle, the forcing conjecture further asserts that asymptotic equality characterizes quasi-random graphs. We establish an adjoint identity for a general class of graph-substitution operators and use it to obtain Sidorenko and forcing results for balanced blow-ups, subdivisions, Cartesian products, and strong products.

math.CO

On the Cost Number of Graphs with Determining Number Two

A distinguishing vertex coloring of a graph $G$ is a vertex coloring such that only the identity automorphism of $G$ preserves the coloring. A graph is $2$-distinguishable if it admits a distinguishing vertex coloring with two colors, and its cost $ρ(G)$ is the minimum size of a color class in such a coloring. The determining number of a graph $G$, denoted by $Det(G)$, is the minimum size of a subset $S\subseteq V(G)$ such that only the trivial automorphism fixes every element of $S$ pointwise. Boutin (J. Combin. Math. Combin. Comput. 85: 161-171, 2013) asked if $ρ(G)$ and $Det(G)$ can be arbitrarily far apart. While the case for $Det(G) = 1$ is trivial, the answer remained unknown for $Det(G) \ge 2$. In this manuscript, we show that if $Det(G)=2$ then not only is $ρ(G)$ bounded, but in fact $ρ(G) \leq 4$. This is the first resolution of Boutin's question for any nontrivial fixed determining number. Moreover, for every fixed $Det(G)= n$, we construct examples giving a lower bound on any possible upper bound for $ρ(G)$ in terms of $n$.

math.CO