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# The Gudermannian Generated Family of Distributions with Characterizations, Regression Models and Applications

Studia Scientiarum Mathematicarum Hungarica
Authors:
Emrah Altun
,
,
Haitham M. Yousof
, and
G. G. Hamedani

This study proposes a new family of continuous distributions, called the Gudermannian generated family of distributions, based on the Gudermannian function. The statistical properties, including moments, incomplete moments and generating functions, are studied in detail. Simulation studies are performed to discuss and evaluate the maximum likelihood estimations of the model parameters. The regression model of the proposed family considering the heteroscedastic structure of the scale parameter is defined. Three applications on real data sets are implemented to convince the readers in favour of the proposed models.

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# On an Equation with Prime Numbers Close to Squares

Studia Scientiarum Mathematicarum Hungarica
Author:
Stoyan I. Dimitrov

Let [ · ] be the fioor function. In this paper, we show that when 1 < c < 37/36, then every sufficiently large positive integer N can be represented in the form

$N = P 1 c + P 2 c + P 3 c ,$

where p1, p2, p3 are primes close to squares.

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# Farey-Subgraphs and Continued Fractions

Studia Scientiarum Mathematicarum Hungarica
Authors:
Seema Kushwaha
and
Ritumoni Sarma

In this article, we study a family of subgraphs of the Farey graph, denoted as N for every N ∈ ℕ. We show that N is connected if and only if N is either equal to one or a prime power. We introduce a class of continued fractions referred to as N -continued fractions for each N > 1. We establish a relation between N -continued fractions and certain paths from infinity in the graph N . Using this correspondence, we discuss the existence and uniqueness of N -continued fraction expansions of real numbers.

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# A Note on Visible Islands

Studia Scientiarum Mathematicarum Hungarica
Authors:
Sophie Leuchtner
,
Carlos M. Nicolás
, and
Andrew Suk

Given a finite point set P in the plane, a subset S⊆P is called an island in P if conv(S) ⋂ P = S. We say that S ⊂ P is a visible island if the points in S are pairwise visible and S is an island in P. The famous Big-line Big-clique Conjecture states that for any k ≥ 3 and l ≥ 4, there is an integer n = n(k, l), such that every finite set of at least n points in the plane contains l collinear points or k pairwise visible points. In this paper, we show that this conjecture is false for visible islands, by replacing each point in a Horton set by a triple of collinear points. Hence, there are arbitrarily large finite point sets in the plane with no 4 collinear members and no visible island of size 13.

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# Lefschetz Open Book Embeddings of 4-Manifolds

Studia Scientiarum Mathematicarum Hungarica
Authors:
Abhijeet Ghanwat
,
Suhas Pandit
, and
A. Selvakumar

In this article, we define the notion of a generalized open book of a n-manifold over the k−sphere Sk , k < n. We discuss Lefschetz open book embeddings of Lefschetz open books of closed oriented 4-manifolds into the trivial open book over S2 of the 7−sphere S7 . If X is the double of a bounded achiral Lefschetz fibration over D2 , then X naturally admits a Lefschetz open book given by the bounded achiral Lefschetz fibration. We show that this natural Lefschetz open book of X admits a Lefschetz open book embedding into the trivial open book over S2 of the 7−sphere S7 .

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# Lifting Generic Maps to Embeddings. Triangulation and Smoothing

Studia Scientiarum Mathematicarum Hungarica
Author:
Sergey A. Melikhov

We show that if a non-degenerate PL map f : NM lifts to a topological embedding in $M × ℝ k$ then it lifts to a PL embedding in there. We also show that if a stable smooth map Nn Mm, mn, lifts to a topological embedding in $M × ℝ$ , then it lifts to a smooth embedding in there.

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# Polynomial Interpolation on Sequences

Mathematica Pannonica
Authors:
Francesc Tugores
and
Laia Tugores

This short note deals with polynomial interpolation of complex numbers verifying a Lipschitz condition, performed on consecutive points of a given sequence in the plane. We are interested in those sequences which provide a bound of the error at the first uninterpolated point, depending only on its distance to the last interpolated one.

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# A Property of Lattices of Sublattices Closed Under Taking Relative Complements and Its Connection to 2-Distributivity

Mathematica Pannonica
Author:
Gábor Czédli

For a lattice L of finite length n, let RCSub(L) be the collection consisting of the empty set and those sublattices of L that are closed under taking relative complements. That is, a subset X of L belongs to RCSub(L) if and only if X is join-closed, meet-closed, and whenever {a, x, b} ⊆ S, yL, xy = a, and xy = b, then yS. We prove that (1) the poset RCSub(L) with respect to set inclusion is lattice of length n + 1, (2) if RCSub(L) is a ranked lattice and L is modular, then L is 2-distributive in András P. Huhn’s sense, and (3) if L is distributive, then RCSub(L) is a ranked lattice.

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# On Derivations and Lie Ideals of Semirings

Mathematica Pannonica
Authors:
and
Neelam

In this paper, centralizing (semi-centralizing) and commuting (semi-commuting) derivations of semirings are characterized. The action of these derivations on Lie ideals is also discussed and as a consequence, some significant results are proved. In addition, Posner’s commutativity theorem is generalized for Lie ideals of semirings and this result is also extended to the case of centralizing (semi-centralizing) derivations of prime semirings. Further, we observe that if there exists a skew-commuting (skew-centralizing) derivation D of S, then D = 0. It is also proved that for any two derivations d 1 and d 2 of a prime semiring S with char S ≠ 2 and x d 1 x d 2 = 0, for all xS implies either d 1 = 0 or d 2 = 0.

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# In Memoriam István Győri

Mathematica Pannonica
Authors:
Ferenc Hartung
and
Mihály Pituk
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