Maximal number of Boolean functions realized by an initial Boolean automaton with two constant states

The problem of realization of Boolean functions by initial Boolean automata with two constant states and n inputs is considered. An initial Boolean automaton with two constant states and n inputs is an initial automaton with output such that in all states the output functions are n-ary constant Boolean functions 0 or 1. The maximum cardinality of set of n-ary Boolean functions, where n > 1, realized by an initial Boolean automaton with two constant states and n inputs is obtained.     

Order of the length of Boolean functions in the class of exclusive-OR sums of pseudoproducts

An exclusive-OR sum of pseudoproducts (ESPP) is a modufo-2 sum of products of affine (linear) Boolean functions. The length of an ESPP is defined as the number of summands in this sum; the length of a Boolean function in the class of ESPPs is the minimum length of an ESPP representing this function. The Shannon length function L ^ESPP(n) on the set of Boolean functions in the class of ESPPs is considered; it is defined as the maximum length of a Boolean function of n variables in the class of ESPPs. It is proved that L ^ESPP(n) = ? (2 ⁿ /n ²). The quantity L ^ESPP(n) also equals the least number l such that any Boolean function of n variables can be represented as a modulo-2 sum of at most l multiaffine functions.     

Estimates for the number of Boolean functions realized by an initial Boolean automaton with three constant states

The problem of realization of Boolean functions by initial Boolean automata with constant states and n inputs is considered. Such automata are those whose output function coincides with one of n-ary constant Boolean functions 0 or 1 in all states. The exact value of the maximum number of n-ary Boolean functions, where n > 1, realized by an initial Boolean automaton with three constant states and n inputs is obtained.     

A study on monotone self-dual Boolean functions

This paper shows that monotone self-dual Boolean functions in irredundant disjuntive normal form (IDNF) do not have more variables than disjuncts. Monotone self-dual Boolean functions in IDNF with the same number of variables and disjuncts are examined. An algorithm is proposed to test whether a monotone Boolean function in IDNF with n variables and n disjuncts is self-dual. The runtime of the algorithm is O(n³).     

Depth of Boolean functions over an arbitrary infinite basis

Realization of Boolean functions by circuits is considered over an arbitrary infinite complete basis. The depth of a circuit is defined as the greatest number of functional elements constituting a directed path from an input of the circuit to its output. The Shannon function of the depth is defined for a positive integer n as the minimal depth D _B (n) of the circuits sufficient to realize every Boolean function on n variables over a basis B. It is shown that, for each infinite basis B, either there exists a constant β ? 1 such that D _B (n) = β for all sufficiently large n or there exist an integer constant γ ? 2 and a constant δ such that log _γ n ? D _B (n) ? log _γ n + δ for all n.     

Certain decompositions of matrices over Abelian rings

A ring R is (weakly) nil clean provided that every element in R is the sum of a (weak) idempotent and a nilpotent. We characterize nil and weakly nil matrix rings over abelian rings. Let R be abelian, and let n ∈ ?. We prove that M ⁿ (R) is nil clean if and only if R/J(R) is Boolean and M _n (J(R)) is nil. Furthermore, we prove that R is weakly nil clean if and only if R is periodic; R/J(R) is ?₃, B or ?₃ ⊕ B where B is a Boolean ring, and that M _n (R) is weakly nil clean if and only if M _n (R) is nil clean for all n ≥ 2.     

On estimates of Shannon functions of the length of unit tests for transpositions of variables

A nontrival upper estimate of the form n √2n (1 + o(1)) is proposed for the Shannon function of the length of the unit checking test for transpositions of variables of a Boolean function from P ₂ ⁿ , and it is proved that the Shannon function of the length of a unit diagnostic test for transpositions of variables of a Boolean function from P ₂ ⁿ has an asymptotics of the form n ²/2.     

On the Complexity and Depth of Embedded in Boolean Cube Circuits That Implement Boolean Functions

A class of circuits of functional elements over the standard basis of the conjunction, disjunction, and negation elements is considered. For each circuit Σ in this class, its depth D(Σ) and dimension R(Σ) equal to the minimum dimension of the Boolean cube allowing isomorphic embedding Σ are defined. It is established that for n = 1, 2,… and an arbitrary Boolean function f of n variables there exists a circuit Σ_f for implementing this function such that R(Σ_f) ? n ? log₂ log₂n + O(1) and D(Σ_f) ? 2n ? 2 log₂ log₂n + O(1). It is proved that for n = 1, 2,… almost all functions of n variables allow implementation by circuits of the considered type, whose depth and dimension differ from the minimum values of these parameters (for all equivalent circuits) by no more than a constant and asymptotically no more than by a factor of 2, respectively.     

Rectifier Circuits of Bounded Depth

Asymptotically tight bounds are obtained for the complexity of computation of the classes of (m, n)-matrices with entries from the set {0, 1,..., q ? 1} by rectifier circuits of bounded depth d, under some relations between m, n, and q. In the most important case of q = 2, it is shown that the asymptotics of the complexity of Boolean (m, n)-matrices, log n = o(m), logm = o(n), is achieved for the circuits of depth 3.     

Universal functions for classes of Boolean polynomials

The following problem is considered: Find Boolean function f of n variables with the property that, given any polynomial p of degree at most s, there exists a set of n-tuples such that p is the only polynomial of degree at most s taking the same values as f at these n-tuples. It is shown that for any fixed s and sufficiently large n, such a function exists and can be chosen from among those with domains of cardinality that grow as O(n ^s ).     

Mean computing time of Boolean operators by programs with restricted memory

The mean computing time for computation of values of Boolean operators by straight-line programs with a conditional stop and the storage of at most D is studied. An asymptotically exact formula for the mean computation time is obtained for growing number n of variables and for almost all Boolean operators with m components in a wide range of D and m.     

The complexity of depth-two information networks

The lower bound Ω(n log₂ n) for the complexity of an arbitrary depth-two information network with n inputs and n outputs is proved providing the inputs are independent, the outputs are independent, and the total information of any input and any output is n times less than the entropy of any input or output. A similar estimate for Boolean depth-two circuits of functional elements is obtained as a corollary.     

Maximal <Emphasis Type="Italic">k</Emphasis>-Intersecting Families of Subsets and Boolean Functions

A family of subsets of an n-element set is k-intersecting if the intersection of every k subsets in the family is nonempty. A family is maximalk-intersecting if no subset can be added to the family without violating the k-intersection property. There is a one-to-one correspondence between the families of subsets and Boolean functions defined as follows: To each family of subsets, assign the Boolean function whose unit tuples are the characteristic vectors of the subsets.We show that a family of subsets is maximal 2-intersecting if and only if the corresponding Boolean function is monotone and selfdual. Asymptotics for the number of such families is obtained. Some properties of Boolean functions corresponding to k-intersecting families are established fork > 2.     

Subdirectly irreducible commutative multiplicatively idempotent semirings

Commutative multiplicatively idempotent semirings were studied by the authors and F. ?vr?ek, where the connections to distributive lattices and unitary Boolean rings were established. The variety of these semirings has nice algebraic properties and hence there arose the question to describe this variety, possibly by its subdirectly irreducible members. For the subvariety of so-called Boolean semirings, the subdirectly irreducible members were described by F. Guzmán. He showed that there were just two subdirectly irreducible members, which are the 2-element distributive lattice and the 2-element Boolean ring. We are going to show that although commutative multiplicatively idempotent semirings are at first glance a slight modification of Boolean semirings, for each cardinal n > 1, there exist at least two subdirectly irreducible members of cardinality n and at least 2ⁿ such members if n is infinite. For \({n \in \{2, 3, 4\}}\) the number of subdirectly irreducible members of cardinality n is exactly 2.     

The depth of Boolean functions realized by circuits over an arbitrary basis

Realization of Boolean functions by circuits of functional elements is considered over arbitrary complete bases (including infinite ones). The depth of a circuit means the maximal number of functional elements forming an oriented chain going from inputs of the circuit to its output. It is shown that for any basis B the growth order of the Shannon function of depth D _B (n) for n → ∞ is equal to 1, log₂ n, or n, and the latter case appears if and only if the basis B is finite.     

Possible isolation number of a matrix over nonnegative integers

Let ?₊ be the semiring of all nonnegative integers and A an m × n matrix over ?₊. The rank of A is the smallest k such that A can be factored as an m × k matrix times a k×n matrix. The isolation number of A is the maximum number of nonzero entries in A such that no two are in any row or any column, and no two are in a 2 × 2 submatrix of all nonzero entries. We have that the isolation number of A is a lower bound of the rank of A. For A with isolation number k, we investigate the possible values of the rank of A and the Boolean rank of the support of A. So we obtain that the isolation number and the Boolean rank of the support of a given matrix are the same if and only if the isolation number is 1 or 2 only. We also determine a special type of m×n matrices whose isolation number is m. That is, those matrices are permutationally equivalent to a matrix A whose support contains a submatrix of a sum of the identity matrix and a tournament matrix.     

A Circuit of Depth Two with Limited Input Branching for Majority Functions

It is shown that a majority Boolean function of n variables can be computed by a depth–2 circuit consisting of majority gates with fan–in n–2 (for each оdd n greater than 5).     

On (<Emphasis Type="Italic">m</Emphasis>, <Emphasis Type="Italic">n</Emphasis>)-absorbing ideals of commutative rings

Let R be a commutative ring with 1 ≠ 0 and U(R) be the set of all unit elements of R. Let m, n be positive integers such that m > n. In this article, we study a generalization of n-absorbing ideals. A proper ideal I of R is called an (m, n)-absorbing ideal if whenever a ₁?a _m ∈I for a ₁,…, a _m ∈R?U(R), then there are n of the a _i ’s whose product is in I. We investigate the stability of (m, n)-absorbing ideals with respect to various ring theoretic constructions and study (m, n)-absorbing ideals in several commutative rings. For example, in a Bézout ring or a Boolean ring, an ideal is an (m, n)-absorbing ideal if and only if it is an n-absorbing ideal, and in an almost Dedekind domain every (m, n)-absorbing ideal is a product of at most m ? 1 maximal ideals.     

On the phase transitions of (<Emphasis Type="Italic">k</Emphasis>, <Emphasis Type="Italic">q</Emphasis>)-SAT

Call a sequence of k Boolean variables or their negations a k-tuple. For a set V of n Boolean variables, let T _k (V) denote the set of all 2 ^k n ^k possible k-tuples on V. Randomly generate a set C of k-tuples by including every k-tuple in T _k (V) independently with probability p, and let Q be a given set of q “bad” tuple assignments. An instance I = (C,Q) is called satisfiable if there exists an assignment that does not set any of the k-tuples in C to a bad tuple assignment in Q. Suppose that θ, q > 0 are fixed and ε = ε(n) > 0 be such that εlnn/lnlnn→∞. Let k ≥ (1 + θ) log₂ n and let \({p_0} = \frac{{\ln 2}}{{q{n^{k - 1}}}}\). We prove that

$$\mathop {\lim }\limits_{n \to \infty } P\left[ {I is satisfiable} \right] = \left\{ {\begin{array}{*{20}c} {1,} & {p \leqslant (1 - \varepsilon )p_0 ,} \\ {0,} & {p \geqslant (1 + \varepsilon )p_0 .} \\ \end{array} } \right.$$

     

Construction of noniterated boolean functions in the basis {&;, ∨, −} and estimation of their number

In this paper we consider noniterated Boolean functions in the basis {&;, ∨, ?}. We obtain the canonical form of the formula for a noniterated function in this basis. We construct the set of such formulas with respect to variables x ₁, …, x _n and calculate the number of its elements. Based on these results, we obtain the upper and lower bounds for the number of noniterated Boolean functions of n variables in the basis under consideration.