Find region given by Exists statement [closed]

I want to find, calculate its volume and visualize the following region most efficiently:

$\Gamma^\delta$ = { $\sigma$: $\exists \sigma' \in \Gamma$ with $F(\sigma,\sigma')\leq 1-\delta^2$}, where

-$\Gamma$ is a convex subset of the Ball with radius 1 (Bloch-sphere),

-$F(\sigma,\sigma')$ is some function where $\sigma$ and $\sigma'$ can be considered vectors in the Ball (actually they are single qubit density matrices and F is the Fidelity).

-$\delta$ is supposed to be small.

Since I'm more or less beginner with Mathematica I would be happy if somebody could give me some tips on that.

closed as off-topic by user9660, MarcoB, Yves Klett, Jason B., m_goldbergFeb 16 '16 at 14:11

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question cannot be answered without additional information. Questions on problems in code must describe the specific problem and include valid code to reproduce it. Any data used for programming examples should be embedded in the question or code to generate the (fake) data must be included." – Community, MarcoB, Yves Klett, Jason B., m_goldberg
If this question can be reworded to fit the rules in the help center, please edit the question.

• This question will be easier to answer and more useful for others if you add a minimal working example of working code and data to show specifically what you are working with. Please edit your question to improve it. Include a minimum example of code that shows the problem and an example of the desired output. – rhermans Feb 16 '16 at 8:32