We prove that for " random " one-relator groups the Delzant T-invariant (which measures the smallest size of a finite presentation of a group) is comparable in magnitude with the length of the defining relator. The proof relies on our previous results regarding isomorphism rigidity of generic one-relator groups and on the methods of the theory of Kolmogorov-Chaitin complexity.

It is proven that the Freiheitssatz holds for all one-relator products of cyclic groups if the relator is cyclically reduced and a proper power. The method of proof involves representing such groups in PSL2(C) and is a refinement of a technique of Baumslag, Morgan and Shalen. The technique allows the extension of the Freiheitssatz result to many additional one-relator products.

An ordered pair X (R) = (X, R ) consisting of a nonvoid set X and a nonvoid family R of binary relations on X is called a relator space. Relator spaces are straightforward generalizations not only of uniform spaces, but also of ordered sets. Therefore, in a relator space we can naturally define not only some topological notions, but also some order theoretic ones. It turns out that these two, a...

If S is noncompact, or has nonempty boundary, then π1(S) is free, and the answer to Question 1 is yes, by an old result of Magnus [7] on one-relator groups. (Essentially, the defining relator in a one-relator group on a given generating set is unique up to conjugacy and inversion.) We will show (see Theorem 3.4 below) that Question 1 also has an affirmative answer in the case of a closed surfac...

Abstract Languages can be divided into three types with respect to the encoding of comitatives and instrumentals: identity, differentiation mixed (Stolz, Stroh Urdze 2013). Diachronic data from Thai dating 13th 21st centuries ce suggests that these language correspond stages development relation between two categories in Thai, which progress as follows. Between mid-18th centuries, employed patt...

We prove that for " most " one-relator groups Delzant's T-invariant (which measures the smallest size of a finite presentation for a group) is comparable in magnitude with the length of the defining relator. The proof relies on our previous results regarding algebraic rigidity of generic one-relator groups and on the methods of algorithmic probability involving Kolmogorov-Chaitin complexity.

Let G D ha; b; : : : j r D 1i be a one-relator group equipped with at least two generators. For all w which do not commute with r in the ambient free group on the generators a, b, ..., the groups G.r;w/ D ha; b; : : : j rrw D r2i are not residually finite and have the same finite images as G. The existence of this family of one-relator groups which are not residually finite reinforces what is b...

When two nominal constituents are in a relation of dependency in the Bantu languages, the syntactically dependent constituent is usually introduced by a relator. In Bantu studies this relator is called connective (also associative, genitive or connexive) element (or pronoun, clitic, prefix, marker or particle). The order is HEAD (R1) RELATOR (REL) DEPENDENT (R2). R1 and R2 are short for first a...

In this paper, we generalise Magnus’ Freiheitssatz and solution to the word problem for one-relator groups by considering one relator quotients of certain classes of right-angled Artin groups and graph products of locally indicable polycyclic groups.

A recent result of D. J. Collins states that the intersection of two Magnus subgroups in a one-relator group consists either just of the ‘obvious’ intersection, or exceptionally of the free product of the obvious intersection with a free group of rank 1. In this paper, Collins’ result is generalised to apply to one-relator products of arbitrary locally-indicable groups. Moreover, a precise anal...