<Emphasis Type=Italic>Eω</Emphasis>-Clifford congruences and <Emphasis Type=Italic>Eω</Emphasis>-<Emphasis Type=Italic>E</Emphasis>-reflexive congruences on an inverse semigroup

This paper enlarges the list of properties of the congruence sequences starting from the universal relation and successively performing the operations of lower T and lower K. Two classes of inverse semigroups, namely Eω-Clifford semigroups and Eω-E-reflexive semigroups, are studied. ((ω _T ) _K ) _T and (((ω _T ) _K ) _T ) _K are found to be the least Eω-Clifford and Eω-E-reflexive congruences on S, respectively. Characterizations of the congruences ((ω _T ) _K ) _T and (((ω _T ) _K ) _T ) _K are developed. The lattices of all Eω-Clifford and Eω-E-reflexive congruences are also studied.     

Optimally small sumsets in groups IV. Counting multiplicities and the <Emphasis Type=Italic>λ</Emphasis><Subscript><Emphasis Type=Italic>G</Emphasis></Subscript> functions

We continue our investigation on how small a sumset can be in a given abelian group. Here small takes into account not only the size of the sumset itself but also the number of elements which are repeated at least twice. A function λ _G (r, s) computing the minimal size (in this sense) of the sum of two sets with respective cardinalities r and s is introduced. (Lower and upper) bounds are obtained, which coincide in most cases. While upper bounds are obtained by constructions, lower bounds follow in particular from the use of a recent theorem by Grynkiewicz.     

Sur la rigidité des groupes de triangles (<Emphasis Type=Italic>r</Emphasis>, <Emphasis Type=Italic>p</Emphasis>, <Emphasis Type=Italic>q</Emphasis>)

We show the length spectral rigidity for the family of fuchsian triangular groups.     

The lattice generated by <Emphasis Type=Italic>τ</Emphasis>-quasicontinuous functions

The lattices generated by the families of quasicontinuous and τ-quasicontinuous functions are described.     

Sufficiency and duality for multiobjective control problems under generalized (<Emphasis Type=Italic>B</Emphasis>, <Emphasis Type=Italic>ρ</Emphasis>)-type I functions

In this paper, we introduce the classes of (B, ρ)-type I and generalized (B, ρ)-type I, and derive various sufficient optimality conditions and mixed type duality results for multiobjective control problems under (B, ρ)-type I and generalized (B, ρ)-type I assumptions.     

Generating <Emphasis Type=Italic>Sym</Emphasis>(<Emphasis Type=Italic>ω</Emphasis>) by Permutations Preserving Dense Orders

We show how generic permutations of ω can be presented by products of permutations preserving dense orders.     

Strengthening of the Kneser theorem on zeros of solutions of the equation <Emphasis Type=Italic>u</Emphasis>″ + <Emphasis Type=Italic>q</Emphasis>(<Emphasis Type=Italic>t</Emphasis>)<Emphasis Type=Italic>u</Emphasis> = 0 using one functional equation

We present conditions under which a linear homogeneous second-order equation is nonoscillatory on a semiaxis and conditions under which its solutions have infinitely many zeros.     

On Baer-Suzuki <Emphasis Type=Italic>π</Emphasis>-theorems

Given a set π of primes, say that the Baer-Suzuki π-theorem holds for a finite group G if only an element of O _π(G) can, together with each conjugate element, generate a π-subgroup. We find a sufficient condition for the Baer-Suzuki π-theorem to hold for a finite group in terms of nonabelian composition factors. We show also that in case 2 ∉ π the Baer-Suzuki π-theorem holds for every finite group.     

Calibration relations for <Emphasis Type=Italic>B</Emphasis><Subscript><Emphasis Type=Italic>φ</Emphasis></Subscript>-splines of fourth order

We study necessary and sufficient conditions for the smoothness of (not necessarily polynomial) splines of fourth order. We establish the uniqueness of a space of splines of maximal smoothness and prove embeddings on refined grids. We also obtain the corresponding calibration relations. Bibliography: 12 titles.     

On the identification <Emphasis Type=Italic>H</Emphasis> = <Emphasis Type=Italic>H</Emphasis>′ in the Lions theorem and a related inaccuracy

We show that the common identification of H with its dual space in the famous functional frame V ⊂ H = H′ ⊂ V′ is incompatible with the distributional frame for some standard pdes and we recall an error related to this unnecessary identification which is repeated from years.     

On the asymptotic optimality of the <Emphasis Type=Italic>cμ</Emphasis>/<Emphasis Type=Italic>θ</Emphasis> rule under ergodic cost

We consider an overloaded multi-server multi-class queueing model where customers may abandon while waiting to be served. For class i, service is provided at rate μ _i , and abandonment occurs at rate θ _i . In a many-server fluid regime, we show that prioritizing the classes in decreasing order of c _i μ _i /θ _i asymptotically minimizes an ergodic holding cost, where c _i denotes the equivalent holding cost per unit time for class i.     

Renormalization group and the <Emphasis Type=Italic>ɛ</Emphasis>-expansion: Representation of the <Emphasis Type=Italic>β</Emphasis>-function and anomalous dimensions by nonsingular integrals

In the framework of the renormalization group and the ɛ-expansion, we propose expressions for the β-function and anomalous dimensions in terms of renormalized one-irreducible functions. These expressions are convenient for numerical calculations. We choose the renormalization scheme in which the quantities calculated using R operations are represented by integrals that do not contain singularities in ɛ. We develop a completely automated calculation system starting from constructing diagrams, determining relevant subgraphs, combinatorial coefficients, etc., up to determining critical exponents. As an example, we calculate the critical exponents of the φ ³ model in the order ɛ ⁴ .     

A theorem on strongly <Emphasis Type="Italic">η</Emphasis>-representable sets

In this paper we consider strongly η-representable sets. We prove that the union of Σ ₂ ⁰ and Π ₂ ⁰ -sets is strongly η-representable.