A Note on The Two-Functional Conjecture

Let D={z:|z|<1} and let K(D) denote the set of all functions analytic in D with the usual topology of uniform convergence on compact subsets of D. Let S be the class of function f(z) =z+a_2z~2+…analytic and univalent in D. Then S is a compact subset of K(D). A function f∈S is said to be a support point of S if it maximizes Re{L} over S for some continuous comp-     

A Note on Shen’s Conjecture on Groups with Given Same-Order Type

Mathematical Notes - Let $$G$$ be a group. Define an equivalence relation $$sim$$ on $$G$$ as follows: for $$x,y in G$$ , $$x sim y$$ if $$x$$ and $$y$$ have same order. The set of sizes of...     

Note on a Conjecture of Gopakumar-Vafa

We rephrase the Gopakumar-Vafa conjecture on genus zero Gromov-Witten invariants of Calabi-Yau threefolds in terms of the virtual degree of the moduli of pure dimension one stable sheaves and investigate the conjecture for K3 fibred local Calabi-Yau threefolds.     

A Note on S-Nakayama’s Lemma

Ukrainian Mathematical Journal - We propose an S-version of Nakayama’s lemma. Let R be a commutative ring, let S be a multiplicative subset of R, and let M be an S-finite R-module. Also let I...     

A Note on Schnyder’s Theorem

We give an alternate proof of Schnyder’s Theorem, that the incidence poset of a graph G has dimension at most three if and only if G is planar.     

A Note on Lewin’s Problem

The parameter l(G) for a primitive digraph G introduced by Lewin is the minimum positive integer k for which there are walks of both lengths k and k + 1 from some vertex u to some vertex v. We obtain upper bounds on l(G) if G is primitive ministrong, or G is just primitive and not necessarily ministrong, or G is primitive symmetric. We also discuss the numbers attainable as l(G).AMS Subject Classification (2000): 05C20, 15A48Partially supported by the National Natural Science Foundation of China (19771040) and the Guangdong Provincial Natural Science Foundation of China (990447).     

A Counterexample to Wegner’s Conjecture on Good Covers

In 1975 Wegner conjectured that the nerve of every finite good cover in ℝ ^d is d-collapsible. We disprove this conjecture.     

A Comment on Ryser’s Conjecture for Intersecting Hypergraphs

Let \(\tau({\mathcal{H}})\) be the cover number and \(\nu({\mathcal{H}})\) be the matching number of a hypergraph \({\mathcal{H}}\). Ryser conjectured that every r-partite hypergraph \({\mathcal{H}}\) satisfies the inequality \(\tau({\mathcal{H}}) \leq (r-1) \nu ({\mathcal{H}})\). This conjecture is open for all r ≥ 4. For intersecting hypergraphs, namely those with \(\nu({\mathcal{H}}) = 1\), Ryser’s conjecture reduces to \(\tau({\mathcal{H}}) \leq r-1\). Even this conjecture is extremely difficult and is open for all r ≥ 6. For infinitely many r there are examples of intersecting r-partite hypergraphs with \(\tau({\mathcal{H}}) = r-1\), demonstrating the tightness of the conjecture for such r. However, all previously known constructions are not optimal as they use far too many edges. How sparse can an intersecting r-partite hypergraph be, given that its cover number is as large as possible, namely \(\tau({\mathcal{H}}) \ge r-1\)? In this paper we solve this question for r ≤ 5, give an almost optimal construction for r = 6, prove that any r-partite intersecting hypergraph with τ(H) ≥ r ? 1 must have at least \((3-\frac{1}{\sqrt{18}})r(1-o(1)) \approx 2.764r(1-o(1))\) edges, and conjecture that there exist constructions with Θ(r) edges.     

Note on Enomoto and Ota’s Conjecture for Short Paths in Large Graphs

With sufficient minimum degree sum, Enomoto and Ota conjectured that for any selected set of vertices, there exists a spanning collection of disjoint paths, each starting at one of the selected vertices and each having a prescribed length. Using the Regularity Lemma, we prove that this claim holds without the spanning assumption if the vertex set of the host graph is sufficiently large.     

A Conjecture on Veronese Generating Submanifolds

In this paper,the higher dimensional conjecture on Veronese generating subman-ifolds proposed by Prof. SUN Zhen-zu is generalized to Pseudo-Euclidean Space L1(m+1), it is proved that in the higher dimentional Lorentz Space L1(m+1), the generating submanifolds of an n dimentional submanifold of Pseudo-Riemannian unit sphere S1m is an n+1 dimentional minimal submanifold of S1(m+1) in L1(m+2) and is of 1-type in L1(m+2).     

A Counter Example on Faudree-Schelp Conjecture

Let simple graph G=(V, E),V=n,E=m. If there exists a path containing i vertices connecting u and v in V, then property P_i(u,v) will be said to told.For 2≤i≤n, let S_i be the set of all unordered pairs of distinct u and v for which property P_i(u.v) holds, and Let S_1 be the set of all unordered pairs of vertices which are not connected by any path. A graph G satisfies property P_i if |S_i|=n(n-1)/2.     

A Note on Stochastic Burgers’ System of Equations

Abstract

We consider a stochastic version of a system of two equations formulated by Burgers [Burgers, J.M. Mathematical examples illustrating relations occurring in the theory of turbulent fluid motion. Verh. Kon. Nerderl. Akad. Weten-Schappen Amsterdam, Afdeel Natuurkunde, 1939, 17 (2), 1–53] with the aim to describe the laminar and turbulent motions of a fluid in a channel. The existence and uniqueness theorem for a global solution is established. The paper generalizes the result from the paper by Da Prato and Ga¸tarek [Da Prato, G.; Ga¸tarek, D. Stochastic Burgers equation with correlated noise. Stochastics Stochastics Rep. 1995, 52, 29–41] dealing with the equation describing only the turbulent motion.     

A Note on a Generalisation of Ore’s Condition

The purpose of this note is to study the problem of cyclability under the condition called regional Ores condition. As a consequence, we get the hamiltonicity of a graph G for which Ores condition holds in each of k vertex subsets partitioning V(G) separately (regionally), provided that the graph is k connected.The work was done while two last authors were visiting L R I. This stay was partially supported by french-polish programme POLONIUM     

A Note on Orthogonal Multiplication

Hurewicz-Radon theorem [1] gives a sufficient and necessary condition about the existence of an orthogonal multiplication f:Rk×Rn→Rn. In this paper,we shall discuss two extensions of the theorem.that is,the sufficient and necessary conditions about the existence of an orthogonal multiplication f:Rk×Rn→Rn 1or f:Rk×Rn→Rn 2     

A Note on Hamiltonian Grids

A complete grid G_(m,n) is the cartesian product of two paths P_m and P_n. In this paper, it is proved that a class of complete grids with two vertices removed are hamiltonian. This result settles a conjecture of S.M. Hedetniemi, S.T. Hede tniemi and P.J. Slater in positive.     

A Note on Zorn's Theorem

In this note, we prove that if G is a finite group, then G is p-nilpotent if and only if there exists a positive integer n such that for any x,y∈G.     

A Note on Supplementing Radicals

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