scholarly journals Full rainbow matchings in graphs and hypergraphs

2021 ◽  
pp. 1-19
Author(s):  
Pu Gao ◽  
Reshma Ramadurai ◽  
Ian M. Wanless ◽  
Nick Wormald
Keyword(s):  
Open Problem ◽  
Affirmative Answer ◽  
Simple Graph ◽  
Rainbow Matching ◽  
Special Case

Abstract Let G be a simple graph that is properly edge-coloured with m colours and let \[\mathcal{M} = \{ {M_1},...,{M_m}\} \] be the set of m matchings induced by the colours in G. Suppose that \[m \leqslant n - {n^c}\] , where \[c > 9/10\] , and every matching in \[\mathcal{M}\] has size n. Then G contains a full rainbow matching, i.e. a matching that contains exactly one edge from M i for each \[1 \leqslant i \leqslant m\] . This answers an open problem of Pokrovskiy and gives an affirmative answer to a generalization of a special case of a conjecture of Aharoni and Berger. Related results are also found for multigraphs with edges of bounded multiplicity, and for hypergraphs. Finally, we provide counterexamples to several conjectures on full rainbow matchings made by Aharoni and Berger.

Norm inequalities for positive semi-definite matrices and a question of Bourin II

2021 ◽  
pp. 2150043
Author(s):  
Mostafa Hayajneh ◽  
Saja Hayajneh ◽  
Fuad Kittaneh
Keyword(s):  
Affirmative Answer ◽  
Unitarily Invariant Norm ◽  
Norm Inequalities ◽  
Invariant Norm ◽  
Special Case

Let [Formula: see text] and [Formula: see text] be [Formula: see text] positive semi-definite matrices. It is shown that [Formula: see text] for every unitarily invariant norm. This gives an affirmative answer to a question of Bourin in a special case. It is also shown that [Formula: see text] for [Formula: see text] and for every unitarily invariant norm.

scholarly journals Multiple points and Wallman compactifications

1975 ◽  
Vol 20 (3) ◽  
pp. 274-280
Author(s):  
Olav Njastad
Keyword(s):  
Quotient Space ◽  
Affirmative Answer ◽  
Multiple Points ◽  
Hausdorff Compactifications ◽  
Tychonoff Spaces ◽  
Special Case

Banaschewski (1963) and Frink (1964) generalized the compactification procedure of Wallman to obtain Hausdorff compactifications of Tychonoff spaces. Numerous papers have been devoted to the problem whether all Hausdorff compactifications may be obtained in this way, and for many classes of compactifications an affirmative answer has been given. This note is a contribution in this direction. We show that if a (Hausdorff) compactification αX of X is the quotient space of a Wallman compactification γX in such a way that the set of multiple points of αX with respect to γX is not too large, then αX too is a Wallman compactification. The results are generalizations of earlier results of Steiner and Steiner (1968) and by the author (1966) for the special case that γX is the Stone Čech-compactification.

scholarly journals On composition of formal power series

2002 ◽  
Vol 30 (12) ◽  
pp. 761-770 ◽  
Author(s):  
Xiao-Xiong Gan ◽  
Nathaniel Knox
Keyword(s):  
Power Series ◽  
Formal Power Series ◽  
Open Problem ◽  
Constant Term ◽  
Radius Of Convergence ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Necessary And Sufficient ◽  
Formal Power ◽  
Special Case

Given a formal power seriesg(x)=b0+b1x+b2x2+⋯and a nonunitf(x)=a1x+a2x2+⋯, it is well known that the composition ofgwithf,g(f(x)), is a formal power series. If the formal power seriesfabove is not a nonunit, that is, the constant term offis not zero, the existence of the compositiong(f(x))has been an open problem for many years. The recent development investigated the radius of convergence of a composed formal power series likefabove and obtained some very good results. This note gives a necessary and sufficient condition for the existence of the composition of some formal power series. By means of the theorems established in this note, the existence of the composition of a nonunit formal power series is a special case.

scholarly journals Iterated nonexpansive mappings in Hilbert spaces

2021 ◽  
Vol 23 (4) ◽  
Author(s):  
Bozena Piatek
Keyword(s):  
Fixed Point ◽  
Hilbert Spaces ◽  
Fixed Point Theory ◽  
Compact Convex ◽  
Nonexpansive Mappings ◽  
Normal Structure ◽  
Point Theory ◽  
Affirmative Answer ◽  
Weakly Compact ◽  
Special Case

AbstractIn [T. Dominguez Benavides and E. Llorens-Fuster, Iterated nonexpansive mappings, J. Fixed Point Theory Appl. 20 (2018), no. 3, Paper No. 104, 18 pp.], the authors raised the question about the existence of a fixed point free continuous INEA mapping T defined on a closed convex and bounded subset (or on a weakly compact convex subset) of a Banach space with normal structure. Our main goal is to give the affirmative answer to this problem in the very special case of a Hilbert space.

OPERATING FUNCTIONS ON MODULATION AND WIENER AMALGAM SPACES

2017 ◽  
Vol 230 ◽  
pp. 72-82 ◽  
Author(s):  
MASAHARU KOBAYASHI ◽  
ENJI SATO
Keyword(s):  
Open Problem ◽  
Composition Operators ◽  
Affirmative Answer ◽  
Modulation Spaces ◽  
Wiener Amalgam Spaces ◽  
Amalgam Spaces ◽  
Funct Anal

The goal of this paper is to characterize the operating functions on modulation spaces$M^{p,1}(\mathbb{R})$and Wiener amalgam spaces$W^{p,1}(\mathbb{R})$. This characterization gives an affirmative answer to the open problem proposed by Bhimani (Composition Operators on Wiener amalgam Spaces, arXiv: 1503.01606) and Bhimani and Ratnakumar (J. Funct. Anal.270(2016), pp. 621–648).

scholarly journals Stabilizer extent is not multiplicative

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 400
Author(s):  
Arne Heimendahl ◽  
Felipe Montealegre-Mora ◽  
Frank Vallentin ◽  
David Gross
Keyword(s):  
Open Problem ◽  
Efficient Algorithm ◽  
Tensor Products ◽  
Affirmative Answer ◽  
The State ◽  
Quantum Circuits ◽  
Classical Simulation ◽  
Important Open Problem ◽  
Classical Computer ◽  
Stabilizer States

The Gottesman-Knill theorem states that a Clifford circuit acting on stabilizer states can be simulated efficiently on a classical computer. Recently, this result has been generalized to cover inputs that are close to a coherent superposition of logarithmically many stabilizer states. The runtime of the classical simulation is governed by the stabilizer extent, which roughly measures how many stabilizer states are needed to approximate the state. An important open problem is to decide whether the extent is multiplicative under tensor products. An affirmative answer would yield an efficient algorithm for computing the extent of product inputs, while a negative result implies the existence of more efficient classical algorithms for simulating largescale quantum circuits. Here, we answer this question in the negative. Our result follows from very general properties of the set of stabilizer states, such as having a size that scales subexponentially in the dimension, and can thus be readily adapted to similar constructions for other resource theories.

scholarly journals AN AFFIRMATIVE ANSWER TO QUASI-CONTRACTION'S OPEN PROBLEM UNDER SOME LOCAL CONSTRAINTS IN JS-METRIC SPACES

2019 ◽  
Vol 24 (3) ◽  
pp. 445-456
Author(s):  
Sanaz Pourrazi ◽  
Farshid Khojasteh ◽  
Mojgan Javahernia ◽  
Hasan Khandani
Keyword(s):  
Fixed Point ◽  
Fixed Points ◽  
Open Problem ◽  
Metric Spaces ◽  
Hausdorff Metric ◽  
Affirmative Answer ◽  
Point Property ◽  
Open Problems ◽  
Local Constraints ◽  
Strict Fixed Point

In this work, we first present JS-Pompeiu-Hausdorff metric in JS metric spaces and then introduce well-behaved quasi-contraction in order to find an affirmative answer to quasi-contractions’ open problem under some local constraints in JS-metric spaces. In the literature, this problem solved when the constant modules α ∈ [0,1/2] and when α ∈ (1/2,1], finding conditions by which the set of all fixed points be non-empty, has remained open yet. Moreover, we support our result by a notable example. Finally, by taking into account the approximate strict fixed point property we present some worthwhile open problems in these spaces.

scholarly journals Fixed Points and Generalized Hyers-Ulam Stability

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
L. Cădariu ◽  
L. Găvruţa ◽  
P. Găvruţa
Keyword(s):  
Fixed Point ◽  
Fixed Point Theorem ◽  
Fixed Points ◽  
Point Theorem ◽  
Open Problem ◽  
Functional Equations ◽  
Affirmative Answer ◽  
Ulam Stability ◽  
Single Variable ◽  
Result Show

In this paper we prove a fixed-point theorem for a class of operators with suitable properties, in very general conditions. Also, we show that some recent fixed-points results in Brzdęk et al., (2011) and Brzdęk and Ciepliński (2011) can be obtained directly from our theorem. Moreover, an affirmative answer to the open problem of Brzdęk and Ciepliński (2011) is given. Several corollaries, obtained directly from our main result, show that this is a useful tool for proving properties of generalized Hyers-Ulam stability for some functional equations in a single variable.

The Trials and Troubles and Grievances of a Private Asylum Superintendent

1894 ◽  
Vol 40 (170) ◽  
pp. 345-354
Author(s):  
Lionel A. Weatherly
Keyword(s):  
Affirmative Answer ◽  
Special Case

When our worthy Secretary asked me to read a paper, my difficulty in giving a direct affirmative answer was not so much the trouble and time the writing of such a paper would involve, but rather the choice of a subject. To give the outlines of some special case, to make a few remarks, and to hear the President, after thanking me, and waiting in solemn silence for the spirit to move some member to start a discussion, call upon the reader of the next paper, did not strike me as worth the trouble; besides, one cannot always have a “special case” on tap in a small private asylum.

On the structures inside truth-table degrees

2001 ◽  
Vol 66 (2) ◽  
pp. 731-770 ◽  
Author(s):  
Frank Stephan
Keyword(s):  
Finite Number ◽  
Open Problem ◽  
Affirmative Answer ◽  
Truth Table ◽  
Turing Degrees ◽  
Positive Degree

AbstractThe following theorems on the structure inside nonrecursive truth-table degrees are established: Dëgtev's result that the number of bounded truth-table degrees inside a truth-table degree is at least two is improved by showing that this number is infinite. There are even infinite chains and antichains of bounded truth-table degrees inside every truth-table degree. The latter implies an affirmative answer to the following question of Jockusch: does every truth-table degree contain an infinite antichain of many-one degrees? Some but not all truth-table degrees have a least bounded truth-table degree. The technique to construct such a degree is used to solve an open problem of Beigel, Gasarch and Owings: there are Turing degrees (constructed as hyperimmune-free truth-table degrees) which consist only of 2-subjective sets and therefore do not contain any objective set. Furthermore, a truth-table degree consisting of three positive degrees is constructed where one positive degree consists of enumerable semirecursive sets, one of coenumerable semirecursive sets and one of sets, which are neither enumerable nor coenumerable nor semirecursive. So Jockusch's result that there are at least three positive degrees inside a truth-table degree is optimal. The number of positive degrees inside a truth-table degree can also be some other odd integer as for example nineteen, but it is never an even finite number.

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