What is a superrigid subgroup ?
نویسنده
چکیده
It is not difficult to see that every group homomorphism from Z to R extends to a homomorphism from R to R. (Essentially, this is the fact that a linear transformation can be defined to have any desired action on a basis.) We will see other examples of discrete subgroups Γ of connected groups G, such that the homomorphisms defined on Γ can (“almost”) be extended to homomorphisms defined on all of G.
منابع مشابه
Introduction to arithmetic groups
Arithmetic groups are fundamental groups of locally symmetric spaces. We will see how they are constructed, and discuss some of their important properties. For example, although the Q-rank of an arithmetic group is usually defined in purely algebraic terms, we will see that it provides important information about the geometry and topology of the corresponding locally symmetric space. Algebraic ...
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