the triple factorization of a group $g$ has been studied recently showing that $g=aba$ for some proper subgroups $a$ and $b$ of $g$, the definition of rank-two geometry and rank-two coset geometry which is closely related to the triple factorization was defined and calculated for abelian groups. in this paper we study two infinite classes of non-abelian finite groups $d_{2n}$ and $psl(2,2^{n})$...

In order to find elliptic curves over Q with large rank, J.-F. Mestre [1991] constructed an infinite family of elliptic curves with rank at least 12. Then K. Nagao [1994] and S. Kihara [1997b] found infinite subfamilies of rank 13 and 14, respectively. By specialization, elliptic curves of rank at least 21 [Nagao and Kouya 1994], 22 [Fermigier 1997], and 23 [Martin and McMillen 1997] have also ...

We study dimension theory for the C∗-algebras of row-finite k-graphs with no sources. We establish that strong aperiodicity—the higher-rank analogue of condition (K)—for a k-graph is necessary and sufficient for the associated C∗-algebra to have topological dimension zero. We prove that a purely infinite 2-graph algebra has real-rank zero if and only if it has topological dimension zero and sat...

In 1990, Cook, Kannan and Schrijver proved that the split closure (the 1st 1-branch split closure) of a polyhedron is again a polyhedron. They also gave an example of a 3-dimensional mixed-integer polytope whose 1-branch split rank is infinite. We generalize this example to a family of high-dimensional polytopes and present a closed-form description of the kth 1-branch split closure of these po...

Bounded, semi-infinite Hankel matrices of finite rank over the space l of square-summable sequences occur frequently in classical analysis and engineering applications. The notion of finite rank often appears under different contexts and the literature is diverse. The first part of this paper reviews some elegant, classic criteria and establish connections among the various characterizations of...

To every infinite lower Hessenberg matrix D is associated a linear operator on l2. In this paper we prove the similarity of the operator D − ∆, where ∆ belongs to a certain class of compact operators, to the operator D−∆′, where ∆′ is of rank one. We first consider the case when ∆ is lower triangular and has finite rank; then we extend this to ∆ of infinite rank assuming that D is bounded. In S...

Let k be an imaginary quadratic number field with Ck,2, the 2-Sylow subgroup of its ideal class group Ck, of rank 4. We show that k has infinite 2-class field tower for particular families of fields k, according to the 4-rank of Ck, the Kronecker symbols of the primes dividing the discriminant ∆k of k, and the number of negative prime discriminants dividing ∆k. In particular we show that if the...