MacWilliams duality and a Gleason-type theorem on self-dual bent functions

We prove that the MacWilliams duality holds for bent functions. It enables us to derive the concept of formally self-dual Boolean functions with respect to their near weight enumerators. By using this concept, we prove the Gleason-type theorem on self-dual bent functions. As an application, we provide the total number of (self-dual) bent functions in two and four variables obtaining from formally self-dual Boolean functions.     

A duality for Boolean algebras with operators

Jónsson and Tarski's extension and representation theorems for Boolean algebras with operators ([7], p. 926 and p. 933) can be extended to homomorphisms between these algebras. The result obtained takes the form of a duality between the category of Boolean algebras with operators and that of the “algebras in the wider sense” (whose subjects are defined in [7]) with a suitable topology. This duality generalizes results of Pierce ([10], p. 38). Moreover, it can be extended to more general objects such as Boolean algebras with non-normal operators and even to arbitrary distributive lattices with operators.     

Normal Boolean functions

Dobbertin (Construction of bent functions and balanced Boolean functions with high nonlinearity, in: Fast Software Encryption, Lecture Notes in Computer Science, Vol. 1008, Springer, Berlin, 1994, pp. 61–74) introduced the normality of bent functions. His work strengthened the interest for the study of the restrictions of Boolean functions on k-dimensional flats providing the concept of k-normality. Using recent results on the decomposition of any Boolean functions with respect to some subspace, we present several formulations of k-normality. We later focus on some highly linear functions, bent functions and almost optimal functions. We point out that normality is a property for which these two classes are strongly connected. We propose several improvements for checking normality, again based on specific decompositions introduced in Canteaut et al. (IEEE Trans. Inform. Theory, 47(4) (2001) 1494), Canteaut and Charpin (IEEE Trans. Inform. Theory). As an illustration, we show that cubic bent functions of 8 variables are normal.     

Invex-convexlike functions and duality

We define a class of invex-convexlike functions, which contains all convex, pseudoconvex, invex, and convexlike functions, and prove that the Kuhn-Tucker sufficient optimality condition and the Wolfe duality hold for problems involving such functions. Applications in control theory are given.The author is grateful to Professor W. Stadler and the referees for many valuable remarks and suggestions, which have enabled him to improve considerably the paper.     

Polynomial expansions of Boolean functions with respect to nondegenerate functions

Translated from Algebra i Logika, Vol. 30, No. 6, pp. 631–637, November–December, 1991.     

A refinement of Stone duality to skew Boolean algebras

We establish two theorems that refine the classical Stone duality between generalized Boolean algebras and locally compact Boolean spaces. In the first theorem, we prove that the category of left-handed skew Boolean algebras whose morphisms are proper skew Boolean algebra homomorphisms is equivalent to the category of étale spaces over locally compact Boolean spaces whose morphisms are étale space cohomomorphisms over continuous proper maps. In the second theorem, we prove that the category of left-handed skew Boolean -algebras whose morphisms are proper skew Boolean -algebra homomorphisms is equivalent to the category of étale spaces with compact clopen equalizers over locally compact Boolean spaces whose morphisms are injective étale space cohomomorphisms over continuous proper maps.     

On designated-weight Boolean functions with highest algebraic immunity

Algebraic immunity has been considered as one of cryptographically significant properties for Boolean functions. In this paper, we study ∑d-1 i=0 (ni)-weight Boolean functions with algebraic immunity achiev-ing the minimum of d and n - d + 1, which is highest for the functions. We present a simpler sufficient and necessary condition for these functions to achieve highest algebraic immunity. In addition, we prove that their algebraic degrees are not less than the maximum of d and n - d + 1, and for d = n1 +2 their nonlinearities equalthe minimum of ∑d-1 i=0 (ni) and ∑ d-1 i=0 (ni). Lastly, we identify two classes of such functions, one having algebraic degree of n or n-1.     

On generalized Boolean functions i

In this paper we introduce the concept of generalized Boolean function. Such a function has its arguments and values in a Boolean algebra and can be written in a manner similar to the canonical disjunctive form, but instead of the product of simple or complemented variables, the product of values of certain functions is used. Every Boolean function is a generalized Boolean one but the converse is not true. The set of all generalized Boolean function “generated” by some fixed function is a Boolean algebra.     

Influences of monotone Boolean functions

Recently, Keller and Pilpel conjectured that the influence of a monotone Boolean function does not decrease if we apply to it an invertible linear transformation. Our aim in this short note is to prove this conjecture.     

Compositional complexity of Boolean functions

We define two measures, γ and c, of complexity for Boolean functions. These measures are related to issues of functional decomposition which (for continuous functions) were studied by Arnol'd, Kolmogorov, Vitu?kin and others in connection with Hilbert's 13th Problem. This perspective was first applied to Boolean functions in [1]. Our complexity measures differ from those which were considered earlier [3, 5, 6, 9, 10] and which were used by Ehrenfeucht and others to demonstrate the great complexity of most decision procedures. In contrast to other measures, both γ and c (which range between 0 and 1) have a more combinatorial flavor and it is easy to show that both of them are close to 0 for literally all “meaningful” Boolean functions of many variables. It is not trivial to prove that there exist functions for which c is close to 1, and for γ the same question is still open. The same problem for all traditional measures of complexity is easily resolved by statistical considerations.     

On generalized Boolean functions II

This cycle of papers is based on the concept of generalized Bolean functions introduced by the author in the first article of the series. Every generalized Boolean function f:Bⁿ→B can be written in a manner similar to the canonical disjunctive form using some function defined on A×B, where A is a finite subset of B containing 0 and 1. The set of those functions f is denoted by GBF_n[A]. In this paper the following questions are presented: (1) What is the relationship between GBF_n[A₁] and GBF_n[A₂] when A₁A₂. (2) What can be said about GBF_n[A₁∩A₂] and GBF_n[A₁A₂] in comparison with GBF_n[A₁]∩GBF_n[A₂] and GBF_n[A₁]GBF_n[A₂], respectively.     

Exclusion sensitivity of Boolean functions

Recently the study of noise sensitivity and noise stability of Boolean functions has received considerable attention. The purpose of this paper is to extend these notions in a natural way to a different class of perturbations, namely those arising from running the symmetric exclusion process for a short amount of time. In this study, the case of monotone Boolean functions will turn out to be of particular interest. We show that for this class of functions, ordinary noise sensitivity and noise sensitivity with respect to the complete graph exclusion process are equivalent. We also show this equivalence with respect to stability. After obtaining these fairly general results, we study “exclusion sensitivity” of critical percolation in more detail with respect to medium-range dynamics. The exclusion dynamics, due to its conservative nature, is in some sense more physical than the classical i.i.d. dynamics. Interestingly, we will see that in order to obtain a precise understanding of the exclusion sensitivity of percolation, we will need to describe how typical spectral sets of percolation diffuse under the underlying exclusion process.     

Dualization of regular Boolean functions

A monotonic Boolean function is regular if its variables are naturally ordered by decreasing ‘strength’, so that shifting to the right the non-zero entries of any binary false point always yields another false point. Peled and Simeone recently published a polynomial algorithm to generate the maximal false points (MFP's) of a regular function from a list of its minimal true points (MTP's). Another efficient algorithm for this problem is presented here, based on characterization of the MFP's of a regular function in terms of its MTP's. This result is also used to derive a new upper bound on the number of MFP's of a regular function.     

Approximating Boolean functions by OBDDs

In learning theory and genetic programming, OBDDs are used to represent approximations of Boolean functions. This motivates the investigation of the OBDD complexity of approximating Boolean functions with respect to given distributions on the inputs. We present a new type of reduction for one-round communication problems that is suitable for approximations. Using this new type of reduction, we improve a known lower bound on the size of OBDD approximations of the hidden weighted bit function for uniformly distributed inputs to an asymptotically tight bound and prove new results about OBDD approximations of integer multiplication and squaring for uniformly distributed inputs.     

Interior and exterior functions of positive Boolean functions

The interior and exterior functions of a Boolean function f were introduced in Makino and Ibaraki (Discrete Appl. Math. 69 (1996) 209–231), as stability (or robustness) measures of the f. In this paper, we investigate the complexity of two problems -INTERIOR and -EXTERIOR, introduced therein. We first answer the question about the complexity of -INTERIOR left open in Makino and Ibaraki (Discrete Appl. Math. 69 (1996) 209–231); it has no polynomial total time algorithm even if is bounded by a constant, unless P=NP. However, for positive h-term DNF functions with h bounded by a constant, problems -INTERIOR and -EXTERIOR can be solved in (input) polynomial time and polynomial delay, respectively. Furthermore, for positive k-DNF functions, -INTERIOR for two cases in which k=1, and and k are both bounded by a constant, can be solved in polynomial delay and in polynomial time, respectively.     

Boolean functions with a simple certificate for CNF complexity

In this paper we study relationships between CNF representations of a given Boolean function $f$ and essential sets of implicates of $f$. It is known that every CNF representation and every essential set must intersect. Therefore the maximum number of pairwise disjoint essential sets of $f$ provides a lower bound on the size of any CNF representation of $f$. We are interested in functions, for which this lower bound is tight, and call such functions coverable. We prove that for every coverable function there exists a polynomially verifiable certificate (witness) for its minimum CNF size. On the other hand, we show that not all functions are coverable, and construct examples of non-coverable functions. Moreover, we prove that computing the lower bound, i.e. the maximum number of pairwise disjoint essential sets, is $NP$-hard under various restrictions on the function and on its input representation.     

The duality theorem for min-max functions

The set of min-max functions F : ℝⁿ → ℝⁿ is the least set containing coordinate substitutions and translations and closed under pointwise max, min, and function composition. The Duality Conjecture asserts that the trajectories of a min-max function, considered as a dynamical system, have a linear growth rate (cycle time) and shows how this can be calculated through a representation of F as an infimum of max-plus linear functions. We prove the conjecture using an analogue of Howard's policy improvement scheme, carried out in a lattice ordered group of germs of affine functions at infinity. The methods yield an efficient algorithm for computing cycle times.     

Binary linear codes with few weights from Boolean functions

Boolean functions have very nice applications in coding theory and cryptography. In coding theory, Boolean functions have been used to construct linear codes in different ways. The objective of this paper is to construct binary linear codes with few weights using the defining-set approach. The defining sets of the codes presented in this paper are defined by some special Boolean functions and some additional restrictions. First, two families of binary linear codes with at most three or four weights from Boolean functions with at most three Walsh transform values are constructed and the parameters of their duals are also determined. Then several classes of binary linear codes with explicit weight enumerators are produced. Some of the binary linear codes are optimal or almost optimal according to the tables of best codes known maintained at http://www.codetables.de, and the duals of some of them are distance-optimal with respect to the sphere packing bound.