Definition:Simply Connected

Definition
Let $T = \struct{S, \tau}$ be a path-connected topological space.

Also see

 * Equivalence of Definitions of Simple Connectedness
 * Fundamental Group is Independent of Base Point for Path-Connected Space
 * Jordan Curve Characterization of Simply Connected Set, which has a characterization of simply connected open subspaces of the Euclidean plane $\R^2$.