From dmd1@lehigh.edu Fri Jan 26 14:23:24 2001 Return-Path: Received: from ns5-1.CC.Lehigh.EDU (ns5.CC.Lehigh.EDU [128.180.39.43]) by nss4.cc.lehigh.edu (8.11.2/8.11.1) with ESMTP id f0QJNI4199872; Fri, 26 Jan 2001 14:23:19 -0500 Received: (from dmd1@localhost) by ns5-1.CC.Lehigh.EDU (8.8.8/8.8.5) id OAA36326; Fri, 26 Jan 2001 14:18:44 -0500 Message-Id: <200101261918.OAA36326@ns5-1.CC.Lehigh.EDU> Date: Fri, 26 Jan 2001 14:18:42 EST From: dmd1@Lehigh.EDU (DON DAVIS) X-Mailer: SENDM [Version 2.0.17] Subject: example sought To: Distribution.List@lehigh.edu (toplist) Status: RO X-Status: This posting is by your moderator, Don Davis. For my beginning algebraic topology course I would like a nice example of a closed subspace A of a topological space X such that A is contractible but X and X/A do not have the same homotopy type. The purpose of such an example would be to highlight the significance of the result that says that such a thing cannot happen if A is a subcomplex of a CW complex X. Don Davis dmd1@lehigh.edu