Vahlen's Group of Clifford Matrices and Spin-Groups.
A graph is said to be symmetric if its automorphism group acts transitively on its arcs. In this paper, all connected valency seven symmetric graphs of order are classified, where , are distinct primes. It follows from the classification that there is a unique connected valency seven symmetric graph of order , and that for odd primes and , there is an infinite family of connected valency seven one-regular graphs of order with solvable automorphism groups, and there are four sporadic ones...
We enlarge the problem of valuations of triads on so called lines. A line in an -structure (it means that is a semigroup and is an automorphism or an antiautomorphism on such that ) is, generally, a sequence , , (where is the class of finite integers) of substructures of such that holds for each . We denote this line as and we say that a mapping is a valuation of the line in a line if it is, for each , a valuation of the triad in . Some theorems on an existence of...
We prove that the first reduced cohomology with values in a mixing -representation, , vanishes for a class of amenable groups including connected amenable Lie groups. In particular this solves for this class of amenable groups a conjecture of Gromov saying that every finitely generated amenable group has no first reduced -cohomology. As a byproduct, we prove a conjecture by Pansu. Namely, the first reduced -cohomology on homogeneous, closed at infinity, Riemannian manifolds vanishes. We also...