Rational homotopy sphere

In algebraic topology, a rational homotopy

-dimensional manifold with the same rational homotopy groups as the

These serve, among other things, to understand which information the rational homotopy groups of a space can or cannot measure and which attenuations result from neglecting torsion in comparison to the (integral) homotopy groups of the space.

A rational homotopy

with the same rational homotopy groups as the