Hyperbolic space groups are isometry groups, acting discontinuously on the hyperbolic 3-space with compact fundamental domain. One possibility to classify them is to look for fundamental domains of these groups. Here are considered supergroups for four series of groups with simplicial fundamental domains. Considered simplices, denoted in [9] by T19, T46, T59, belong to family F12, while T31 bel...

Hecke proved analytically that when h > 2 or when h = 2 CDS (m/q), q E Z, q > 3, then B(h) = (7: Im I > 0, / Re 7 1 < h/2, [ 7 j > 1) is a fundamental region for the group G(h) = (SA , T), where S,+ : 7 --f 7 + X and T: 7 ---t -l/~. He also showed that B(A) fails to be a fundamental region for all other A > 0 by proving that G(X) is not discontinuous. We give an elementary proof of these facts ...

The most secure type of grasp of a frictionless woorkpiece is the form-closure grasp. However, task constraints may make achieving form-closure impossible or undesirable. In this case, one needs to employ a force-closure 1 grasp. In this paper, we study the subclass of force-closure grasps known as second-order stable grasps, which typically have a small number of contacts. We derive conditions...

In this paper, we study a fundamental domain for Sp(g,Z) ⋉ H (g,h) Z \Hg × C .

We consider the Buffon’s problem for the lattice Rα,a which has the fundamental cell composed by the union of octagon, with all sides of lengths a and the angles (π − α) and ( 2 + α) with α ∈ ] 0, π 2 [ , and of the square with side of length a (see Fig. 1). We determine the probability of intersection of a body test needle of length l, l < a. For α = π 4 we also give the estimate of this proba...

administrative corruption is one of the problems with which most societies are tackling with. nowadays, the approaches are emphasized most that try to prevent such phenomenon rather those exerting punishment to offenders. current research investigates the role of organizational culture as one of preventing factors in decreasing administrative corruption. current research is a practical research...

this study aims to investigate the effective factors on non-development of tourism industry in golestan province. the standard questionnaires are used to doing this descriptive, cross-sectional and tentative that those be scattered after measuring their validity and reliability based on simple-random sampling(for tourists) and taxonomy-sampling(for experts) between tourists and experts. the ana...

This paper presents a method for determining the possible instantaneous motions of a sliding object during multiple contact pushing. The approach consists of two components: a kinematic analysis considering kinematic motion constraints, and a force analysis considering force constraints on the motion. A new representation of the support friction of a sliding object is presented, and the results...

We prove the following: there are infinitely many finite-covolume (resp. cocompact) Coxeter groups acting on hyperbolic space Hn for every n ≤ 19 (resp. n ≤ 6). When n = 7 or 8, they may be taken to be nonarithmetic. Furthermore, for 2 ≤ n ≤ 19, with the possible exceptions n = 16 and 17, the number of essentially distinct Coxeter groups in Hn with noncompact fundamental domain of volume ≤ V gr...