We give a simple proof of the finite presentation of Sela's limit groups by using free actions on R n-trees. We first prove that Sela's limit groups do have a free action on an R n-tree. We then prove that a finitely generated group having a free action on an R n-tree can be obtained from free abelian groups and surface groups by a finite sequence of free products and amalgamations over cyclic ...

We give a simple proof of the finite presentation of Sela’s limit groups by using free actions on Rn–trees. We first prove that Sela’s limit groups do have a free action on an Rn–tree. We then prove that a finitely generated group having a free action on an Rn–tree can be obtained from free abelian groups and surface groups by a finite sequence of free products and amalgamations over cyclic gro...

We indicate which symmetrizable locally compact affine or hyperbolic Kac-Moody groups satisfy Kazhdan’s Property (T), and those that satisfy its strong negation, the Haagerup property. This reveals a new class of hyperbolic Kac-Moody groups satisfying the Haagerup property, namely symmetrizable locally compact Kac-Moody groups of rank 2 or of rank 3 noncompact hyperbolic type. These groups thus...

The main result of the work “The nilpotence conjecture in K-theory of toric varieties” is extended to all coefficient fields of characteristic 0, thus covering the class of genuine toric varieties. 1. The statement Let R be a (commutative) regular ring, M be arbitrary commutative, cancellative, torsion free monoid without nontrivial units, and i be a nonnegative integral number. The nilpotence ...

Let L/K be a finite Galois extension of number fields with Galois group G. Let p be a prime and let r ≤ 0 be an integer. By examining the structure of the p-adic group ring Zp[G], we prove many new cases of the p-part of the equivariant Tamagawa number conjecture (ETNC) for the pair (h(Spec(L))(r),Z[G]). The same methods can also be applied to other conjectures concerning the vanishing of certa...

We expand on Nekov\'a\v{r}'s construction of the plectic half transfer to define a Galois action Hilbert modular varieties. More precisely, we study in unifying fashion Shimura varieties associated groups that differ only centre from $R_{F/\mathbb{Q}}{\rm GL}_2$. actions CM points and set connected components these varieties, show two are compatible. This extends conjecture Nekov\'a\v{r}--Scholl.