To see the original postings to which this refers, go to www.lehigh.edu/~dmd1/postings.html........DMD _____________________________ Date: Mon, 5 Feb 2001 09:58:47 -0800 (PST) From: Kevin Iga Subject: Re: embedding question Thank you, Tom. It seems that this approach may have something to say about whether or not a general manifold can be a codimension 1 embedded hypersurface in R^n. In particular, it must be null-cobordant, but possibly the kinds of handles that can be attached are restricted in some way. Is that more general question known? It also seems that your argument needs n>4, so that we don't know what's going on with S^3 or S^4 (that is, does a possible counterexample to the Poincare conjecture embed in R^4, or does a conjectural exotic 4-sphere embed in R^5). Another natural question that arises from Tom's answer is: If the exotic seven-spheres don't embed in R^8, then where *do* they embed? Thanks. Kevin Iga kiga@pepvax.pepperdine.edu