Floer homology of Brieskorn homology spheres: solution to Atiyah's problem

In this paper we answer the question posed by M.~Atiyah and give an explicit formula for Floer homology of Brieskorn homology spheres in terms of their branching sets over the 3--sphere. We further show how Floer homology is related to other invariants of knots and 3--manifolds, among which are the $\bar\mu$--invariant of W.~Neumann and L.~Siebenmann and the Jones polynomial. Essential progress is made in proving the homology cobordism invariance of our own $\nu$--invariant.