Quasi-projective and quasi-liftable characters

Quasi-projective covers of right $S$-acts

In this paper $S$ is a monoid with a left zero and $A_S$ (or $A$) is a unitary right $S$-act. It is shown that a monoid $S$ is right perfect (semiperfect) if and only if every (finitely generated) strongly flat right $S$-act is quasi-projective. Also it is shown that if every right $S$-act has a unique zero element, then the existence of a quasi-projective cover for each right act implies that ...

Non – Quasi – Projective

quasi-projective covers of right $s$-acts

in this paper $s$ is a monoid with a left zero and $a_s$ (or $a$) is a unitary right $s$-act. it is shown that a monoid $s$ is right perfect (semiperfect) if and only if every (finitely generated) strongly flat right $s$-act is quasi-projective. also it is shown that if every right $s$-act has a unique zero element, then the existence of a quasi-projective cover for each right act implies that ...

Fibred Kähler and quasi-projective groups

We formulate a new theorem giving several necessary and su‰cient conditions in order that a surjection of the fundamental group p1ðX Þ of a compact Kähler manifold onto the fundamental group Pg of a compact Riemann surface of genus gd 2 be induced by a holomorphic map. For instance, it su‰ces that the kernel be finitely generated. We derive as a corollary a restriction for a group G, fitting in...

Exotic Projective Structures and Quasi-fuchsian Space

1. Introduction. Let S be an oriented closed surface of genus g > 1. A projec-tive structure on S is a maximal system of local coordinates modeled on the Riemann sphere C, whose transition functions are Möbius transformations. For a given pro-jective structure on S, we have a pair (f, ρ) of a local homeomorphism f from the universal cover S of S to C, called a developing map, and a group homomo...