Recognition of some symmetric groups by the set of the order of their elements

For a finite group G, let π_e(G) be the set of order of elements in G and denote S _n the symmetric group on n letters. We will show that if π_e(G ) = π_e(H), where H is S _p or S _p+1 and p is a prime with 50 < p < 100, then G ≅ H. This revised version was published online in August 2006 with corrections to the Cover Date.     

Dominions in varieties generated by simple groups

We determine the dominion (in the sense of Isbell) of a subgroup H of a finite nonabelian simple group S in Var(S). We also obtain necessary and suficient conditions for H to be epimorphically embedded in S, and derive several examples, which generalize an example of B. H. Neumann. Finally, we extend the results to a variety generated by a family of finite nonabelian simple groups. Received May 12, 1999; accepted in final form April 9, 2002.     

格蕴涵代数的LI-理想格及其素元刻画

运用格理论的原理和方法对格蕴涵代数L的LI-理想概念作进一步研究.首先,在L的全体LI-理想之集ф_(LI)(L)上定义了格运算■和■,蕴涵运算■以及伪补运算■,证明了(ф_(LI)(L),,■,■,■,{O},L)构成一个完备Heyting代数的结论.其次,利用运算固的性质给出了(ф_(LI)(L),,■,■,■,■,{O},L)成为Boolean代数的若干充要条件.最后,借助于L的素LI-理想之特性获得了格(ф_(LI)(L),,■,■,{O},L)中素元的若干等价刻画.     

The free orthomodular lattice on countably many generators is a subalgebra of the free orthomodular lattice on three generators

We show every at most countable orthomodular lattice is a subalgebra of one generated by three elements. As a corollary we obtain that the free orthomodular lattice on countably many generators is a subalgebra of the free orthomodular lattice on three generators. This answers a question raised by Bruns in 1976 [2] and listed as Problem 15 in Kalmbach's book on orthomodular lattices [6]. Received April 12, 2001; accepted in final form May 6, 2002.     

Generalized resolvents of linear relations generated by a nonnegative operator function and a differential elliptic-type expression

We study invertible extensions of the minimal relation generated by a nonnegative operator function and a differential elliptic-type expression. We prove that the operators inverse to such extensions are integral operators and describe such integral operators. We obtain a formula for generalized resolvents of the minimal relation.     

Generalized difference sequence spaces on seminormed space defined by Orlicz functions

In this paper we define the sequence space ℓ _M (Δ ^m , p, q, s) on a seminormed complex linear space by using an Orlicz function. We study its different algebraic and topological properties like solidness, symmetricity, monotonicity, convergence free etc. We prove some inclusion relations involving ℓ _M (Δ ^m , p, q, s).      

Correction to "Some properties of complete congruence lattices"

Received April 26, 2000; accepted in final form July 19, 2001.     

\mathcal{l} -prime elements in multiplicatice lattices

In this paper we study -prime elements in C-lattices and characterize Prüfer lattices, almost principal element lattices and principal element lattices in terms of -prime elements. Using these results, some new characterizations are given for general ZPI-rings and almost multiplication rings. Finally some new equivalent conditions are given for Dedekind lattices. Received August 18, 2000; accepted in final form April 22, 2002.     

Pappian implies Arguesian for modular lattices

We prove the claim in the title, using Hessemberg's analog theorem for projective planes, and the characterization of non-Arguesian modular lattices provided by Day and Jónsson [5,6]. Received January 22, 1999; accepted in final form May 6, 1999.     

On order-polynomial completeness of lattices

In this note we prove that the cardinality of an infinite order-polynomially complete lattice (if such a lattice exists) must be greater than each , where is defined such that and for . This strengthens the result in [4]. Received November 10, 1995; accepted in final form April 6, 1998.     

A constructive approach to the finite congruence lattice representation problem

A finite lattice is representable if it is isomorphic to the congruence lattice of a finite algebra. In this paper, we develop methods by which we can construct new representable lattices from known ones. The techniques we employ are sufficient to show that every finite lattice which contains no three element antichains is representable. We then show that if an order polynomially complete lattice is representable then so is every one of its diagonal subdirect powers. Received August 30, 1999; accepted in final form November 29, 1999.     

Lattice bimorphisms on f-algebras

Let A, B and C be lattice-ordered algebras and let be a bilinear map. We call a lattice bimorphism if for each and each the partial maps and are lattice homomorphisms of B and A into C, respectively; and we say that is multiplicative if holds in C for all and . In this paper, we study the connection between lattice bimorphisms and multiplicative bilinear maps on f-algebras in great detail. Our central result in this direction is the following: if A, B and C are Archimedean f-algebras with unit elements e _A , e _B and e _C respectively and is a Markov bilinear map (i.e., is positive and (e _A , e _B ) = e _C ) then is a lattice bimorphism if and only if is multiplicative. The main application of this result we present in this work is the Cauchy-Shwarz inequality in Archimedean (not necessarily commutative) d-algebras, which is an improvement of the result of Buskes and van Rooij, who established this inequality in the commutative case. Received April 26, 2001; accepted in final form August 9, 2001.     

Notes on R1-ideals in partial abelian monoids

In the present paper, we deal with a class of R ₁-ideals of cancellative positive partial abelian monoids (CPAMs). We prove that, for I being an R ₁-ideal of a CPAM P, P/I is a CPAM. The lattice of congruence relations associated with R ₁-ideals is a sublattice of the lattice of all equivalence relations. Finally, we prove that an intersection of two Riesz ideals is a Riesz ideal and that the lattice of Riesz ideals is a sublattice of the lattice of all ideals. Received March 19, 1999; accepted in final form December 16, 1999.     

A new characterization of arithmeticity

We prove that an equivalence lattice is arithmetical whenever for every and there exists a compatible choice function modulo , having a as a fixed point. The converse holds if L is finite. Received September 30, 1998; accepted in final form December 1, 1998.     

Mailbox¶A Note on minimal varieties generated by order-primal algebras

We prove that the order-primal algebra of a non-trivial finite connected poset P generates a minimal variety if and only if P is dismantlable. Received November 26, 2002; accepted in final form January 24, 2003.     

Congruence join semidistributivity is equivalent to a congruence identity

We show that a locally finite variety is congruence join semidistributive if and only if it satisfies a congruence identity that is strong enough to force join semidistributivity in any lattice. Received February 9, 2000; accepted in final form November 23, 2000.     

On coatoms in lattices of quasivarieties of algebraic systems

It is found the necessary condition for the lattice of quasivarieties has a finite set of coatoms. In particular if a quasivariety is generated by a finitely generated abelian-by-polycyclic-by-finite group or a totally ordered group then it has a finite set of proper maximal subquasivarieties. Also it is proved that the set of quasiverbal congruence relations of a finitely defined universal algebra is closed under any meets. Received March 23, 1999; accepted in final form June 7, 1999.     

On characterizations of atomistic lattices

In the present paper we characterize atomistic lattices. These characterizations are given in terms of concepts related to pure elements (cf. [4], [6]) and neat elements (cf. [3]).     

A short proof of a theorem of Birkhoff

This paper gives a new proof of a theorem of G. Birkhoff: Every group can be represented as the automorphism group of a distributive lattice D; if is finite, D can be chosen to be finite. The new proof is short, and it is easily visualized. Received November 3, 1995; accepted in final form October 3, 1996.