A Note on the π—regularity of Rings

LetRbeassociativewithanidentity.RingRiscalledaπ-regularringifandonlyifforeveryelementainR,thereexistsomen1,c∈Rsuchthatan=ancan.RingRiscalledaunitπ-regularringifandonlyifforanyelementainR,thereissomem1suchthatam=amuamforaunitu∈R.Manyringsareunitπ-regularrings,suchassemicommutativeπ-regularrings,finitesemicommutativerings,stronglyπ-regularringsandunit-regularrings.Risstronglyπ-regularifforeverya∈Rthereexistn1andc∈Rsuchthatan=an 1c.Ifthein-dexnaboveisoneforalla∈R,thenRiscalledabel…     

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 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 Supplementing Radicals

ＡＮｏｔｅｏｎＳｕｐｐｌｅｍｅｎｔｉｎｇＲａｄｉｃａｌｓＲｉｃｈａｒｄＷｉｅｇａｎｄｔ（ＭａｔｈｅｍａｔｉｃａｌＩｎｓｔｉｔｕｔｅ，ＨｕｎｇａｒｉａｎＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ，Ｐ．Ｏ．Ｂｏｘ１２７，Ｂｕｄａｐｅｓｔ，Ｈｕｎｇａｒｙ）Ａｂｓｔ...     

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 Weakly Implicative Ideal

ＡＮｏｔｅｏｎＷｅａｋｌｙＩｍｐｌｉｃａｔｉｖｅＩｄｅａｌＬｉｕｙｏｎｇｌｉｎ（Ｄｅｐｔ．ｏｆＭａｔｈ．，ＦｕｊｉａｎＴｅａｃｈｅｒ’ｓＣｏｌｌｅｇｅ，Ｎａｎｐｉｎｇ３５３０００）ＡＮｏｔｅｏｎＷｅａｋｌｙＩｍｐｌｉｃａｔｉｖｅＩｄｅａｌＬｉｕｙｏｎ...     

A Note on Aubin-Lions-Dubinskiĭ Lemmas

Strong compactness results for families of functions in seminormed nonnegative cones in the spirit of the Aubin-Lions-Dubinski? lemma are proven, refining some recent results in the literature. The first theorem sharpens slightly a result of Dubinski? (in Mat. Sb. 67(109):609–642, 1965) for seminormed cones. The second theorem applies to piecewise constant functions in time and sharpens slightly the results of Dreher and Jüngel (in Nonlinear Anal. 75:3072–3077, 2012) and Chen and Liu (in Appl. Math. Lett. 25:2252–2257, 2012). An application is given, which is useful in the study of porous-medium or fast-diffusion type equations.     

A Note on Toeplitz’ Conjecture

In 1911, Toeplitz made a conjecture asserting that every Jordan curve in $\mathbb{R}^{2}$ contains four points forming the corners of a square. Here Conjecture C is presented, which states that the side length of the largest square on a closed curve that consists of edges of an n×n grid is at least $1/\sqrt{2}$ times the side length of the largest axis-aligned square contained inside the curve. Conjecture C implies Toeplitz’ conjecture and is verified computationally for n≤13.     

Note on the Paper “A Note on the SVD of Matrices”

Let F be a field, R be an F-algebra having SVD property['], R+ = {a e Rla = a}. In[2], we proved thatLemma 1 Let R be an F-algebra which having SVD proPerty Then R+ is a sub6e1d inF, R+ is a fOrmaIly rea1 6eId, and R+ is Pythagorean with no zerChdivisor.In the proof of Lernma 1 of [2], thereis this step: "FOr any a E R+ l clearly, there ekistsd E R+ n F such that a2 = ad = a', thus a = la E F, is fOllOws that R+ C F".Recently, paper [11 shows that "The proof of this step is no…     

A Note on Property(ω)

In this note we study the property(ω),a variant of Weyl's theorem introduced by Rakoevic,by means of the new spectrum.We establish for a bounded linear operator defined on a Banach space a necessary and sufficient condition for which both property(ω) and approximate Weyl's theorem hold.As a consequence of the main result,we study the property(ω) and approximate Weyl's theorem for a class of operators which we call the λ-weak-H(p) operators.     

A Note on P—Sasakian Manifold

s51.IntroductionLetMbeadifferentiablemanifo1dofdimensionn,ifMadmitsa(l,l)-tensorfieldgl,aPoSitivedefiniteRiemannianmetricg,avectorfieldeandal-formVwhichsatisfythefollow-ingconditions.thensuchamanifoldMiscalledaPara-SasakianmanifoldorbrieflyaP-Sasakianmanifoldby7'.AdatiandK.Matsumoto[ljwhichareconsideredasspecialcaseofanalmostparacontactmanifoldintroducedbyI.Sato[2].WhereVdenotestheoperatorofcovariantdifferentiationwithrespecttothemetrictensorg'X(M)denotesthesetofdifferentiablevectorfiel…     

A Note on the Viscous Cahn-Hilliard Equation

In this note, we study the global existence of classical solutions for the viscous Cahn-Hilliard equation with spatial dimension n ≤ 5. Based on the Schauder type estimates and energy estimates, we establish the global existence of classical solutions.     

A Note on Semigroups of Linear Operators

It is well known[l]that a closed linear operator A with dense domain in(an ordered)Banach space E senerates a C_O—semigroup if and only if the resolvent set p(A)contains(ω,+∞),andsup{‖(λ-ω)~nR(λ,A)~n‖:λ>ω,n∈N}<+∞(1)for someω.Sometimes,the condition(l)is not easy to verify.However,for the socalled resolvent positive operators(that is for someω,p(A)(?)(ω,+∞)and for allλ>ω,R(λ,A)=(λ-A)~1≥0),in[2],there are some easy-verified conditions.Here in thisnote,we establish another easy-verified condition.Let E_+be the positive cone of E,and     

A Note on"Non-independence and Uncorrelatedness

An elementary fact in the theory of probability is that there exists such random varibles X, Y which are both non indepent and uncorrelated. A wellknown example is that (X,Y) has a density function     

A Note on τ-Critical Linear Hypergraphs

J.P. Roudneff as well as R. Aharoni and R. Ziv conjectured that every τ-critical hypergraph has at most $\left( {\begin{array}{*{20}{c}} {\tau + 1} \\ 2 \end{array}} \right)$ edges. In this note we prove this conjecture for τ ≤ 5, and obtain a nontrivial upper bound for general τ.     

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 First Order Differential Equation

In this note, a theorem and its three corollaries on solution of the first order ordinary differential equation are given. Theorem Suppose that b, F∈C,a∈C~1,b(y)≠0. If a(t) and b(t) satisfy the equality a′(t)b(t)=1, (1) then the first order differential equation y′=b(y)F(x,a(y)) (2) has a solution y=f(u) (3) where u=u(x) is a solution of the equatien