We consider the problem of packing squares into bins which are unit squares, where the goal is to minimize the number of bins used. We present an algorithm for this problem with an absolute worst-case ratio of 2, which is optimal provided P ≠ NP. 2000 Mathematics Subject Classification: 68W25, 68W4

We say that a simple graph G is fractional independent-set-deletable k-factor-critical, shortly, fractional ID-k-factor-critical, if G− I has a fractional k-factor for every independent set I of G. Some sufficient conditions for a graph to be fractional ID-k-factor-critical are studied in this paper. Furthermore, we show that the result is best possible in some sense. 2010 Mathematics Subject C...

We prove some coincidence and common fixed point theorems for nonself maps (not necessarily continuous) satisfying different contractive conditions on an arbitrary nonempty subset of a metric space. As applications, we demonstrate the existence of: (i) common fixed points of the maps from the set of best approximations, (ii) solutions to nonlinear eigenvalue problems. Our work sets analogues, u...

Ahlswede, Khachatrian, Mauduit and A. Sárközy introduced the notion family-complexity of families of binary sequences. They estimated the family-complexity of a large family related to Legendre symbol introduced by Goubin, Mauduit and Sárközy. Here their result is improved, and apart from the constant factor the best lower bound is given for the family-complexity. 2000 AMS Mathematics Subject C...

In many applications such as data compression, imaging or genomic data analysis, it is important to approximate a given tensor by a tensor that is sparsely representable. For matrices, i.e. 2-tensors, such a representation can be obtained via the singular value decomposition which allows to compute the best rank k approximations. For t-tensors with t > 2 many generalizations of the singular val...

In the present paper we obtain enhanced estimates regarding the remainder of the alternating harmonic series. More precisely, we show that 1 4n2 +a < ∣ ∣∣ ∣ ∣ n ∑ k=1 (−1)k−1 1 k − (−1)n−1 1 2n − ln2 ∣ ∣∣ ∣ ∣ 1 4n2 +b , for all n ∈N , with a = 2 and b = 2(3−4 ln2) 2 ln2−1 = 1.177398899 . . . . In addition, the constants a and b are the best possible with the above-mentioned property. Mathematic...

We describe mean value estimates for exponential sums of degree exceeding 2 that approach those conjectured to be best possible. The vehicle for this recent progress is the efficient congruencing method, which iteratively exploits the translation invariance of associated systems of Diophantine equations to derive powerful congruence constraints on the underlying variables. There are application...

We consider Hardy’s integral inequality and we obtain some new generalizations of Bicheng-Debnath’s recent results. We derive two distinguished classes of inequalities covering all admissible choices of parameter k from Hardy’s original relation. Moreover, we prove the constant factors involved in the right-hand sides of some particular inequalities from both classes to be the best possible, th...

Arithmetic convolution rings provide a general and unified treatment of many rings that have been called arithmetic; the best known examples are rings of complex valued functions with domain in the set of non-negative integers and multiplication the Cauchy product or the Dirichlet product. The emphasis here is on factorization and related properties of such rings which necessitates prior result...

Let T be a simple k-uniform hypertree with t edges. It is shown that if H is any k-uniform hypergraph with n vertices and with minimum degree at least n k−1 2k−1(k−1)! (1+o(1)), and the number of edges of H is a multiple of t then H has a T -decomposition. This result is asymptotically best possible for all simple hypertrees with at least two edges. Mathematics Subject Classification (1991): 05...