Sharpe, EBryant, RL2016-08-251999-12-010370-2693https://hdl.handle.net/10161/12700It was recently pointed out by E. Witten that for a D-brane to consistently wrap a submanifold of some manifold, the normal bundle must admit a Spinc structure. We examine this constraint in the case of type II string compactifications with vanishing cosmological constant, and argue that in all such cases, the normal bundle to a supersymmetric cycle is automatically Spinc. © 1999 Published by Elsevier Science B.V. All rights reserved.Journal article