The rigidity tag has no usage guidance.

**10**

votes

**0**answers

537 views

### Definition of a uniformly bounded dual of a group

The unitary dual of a group $G$ is the set of equivalence classes of irreducible unitary representations of $G$ with the Fell topology. (This topology is defined using convergence of positive definite ...

**7**

votes

**0**answers

218 views

### quantitative version of the rigidity of the 2-sphere

I am looking for a quantitaive version of the following theorem:
A compact surface with $K\equiv 1$ is isometric to the round sphere.
Of course I get the Berger, Brendle-Schoen Theorem which insures ...

**3**

votes

**0**answers

113 views

### Rigidity vs Super-rigidity of representations (of Kähler/surface groups)

In the literature there are several definitions of "rigidity" (or "super-rigidity") of representations, adapted to the circumastances. I wonder what are the relations between them; I excuse in advance ...

**3**

votes

**0**answers

129 views

### Show that duality functor is anti-monoidal

Let $\mathcal{C}$ be a right rigid (not strict) monoidal category with associativity constraint $\Phi$. Let $J_{UV}: U^*\otimes V^*\to (V\otimes U)^*$ the canonical isomorphism for every objects ...

**2**

votes

**0**answers

195 views

### Rigidity of Diophantine torus translations

Let $T_a:x\mapsto x+a$ be a Diophantine translation on the torus $\mathbb T^d$, $d>1$.
Let $h$ be some $C^1$ diffeomorphism of $\mathbb T^d$ such that
$$
g=h\circ T_a\circ h^{-1}
$$
is $C^\infty$. ...