%0 Journal Article %T Topological equivalences for differential graded algebras %A Daniel Dugger %A Brooke Shipley %J Mathematics %D 2006 %I arXiv %X We investigate the relationship between differential graded algebras (dgas) and topological ring spectra. Every dga C gives rise to an Eilenberg-Mac Lane ring spectrum denoted HC. If HC and HD are weakly equivalent, then we say C and D are topologically equivalent. Quasi-isomorphic dgas are topologically equivalent, but we produce explicit counter-examples of the converse. We also develop an associated notion of topological Morita equivalence using a homotopical version of tilting. %U http://arxiv.org/abs/math/0604259v2