Universal presheaves on group geometries, and modular representations

On the Modular Representations of the Symmetric Group (III).

In a previous paper2 the author commented upon an idea of D. E. Littlewood' for defining the indecomposables of the regular representation of Sn, and showed how it could be utilized to characterize the modular irreducible components. A modification of Littlewood's idea is presented here which throws new light upon the whole problem. Young's rule3 for constructing the "seminormal" representation...

On the Modular Representations of the Symmetric Group (II).

Asymptotic Results on Modular Representations of Symmetric Groups and Almost Simple Modular Group Algebras

In fact, this is a question about infinite simple groups because it is easy for G finite, and because a non-trivial normal subgroup gives rise to a non-trivial ideal different from the augmentation ideal. Also note that the problem reduces easily to the question on when the augmentation ideal is simple as a ring. The first interesting class of groups with almost simple FG was discovered in [3]....

A Universal Investigation of $n$-representations of $n$-quivers

noindent We have two goals in this paper. First, we investigate and construct cofree coalgebras over $n$-representations of quivers, limits and colimits of $n$-representations of quivers, and limits and colimits of coalgebras in the monoidal categories of $n$-representations of quivers. Second, for any given quivers $mathit{Q}_1$,$mathit{Q}_2$,..., $mathit{Q}_n$, we construct a new quiver $math...

The Universal Covering Group of U(n) and Projective Representations

Using fibre bundle theory we construct the universal covering group of U(n), Ũ(n), and show that Ũ(n) is isomorphic to the semidirect product SU(n)©s R. We give a bijection between the set of projective representations of U(n) and the set of equivalence classes of certain unitary representations of SU(n) ©s R. Applying Bargmann’s theorem, we give explicit expressions for the liftings of project...