Timeline for Weakly contractible $X$, but none of the maps $*\to X$ are cofibrations

9 events

when toggle format	what		by	license	comment
Jan 17 at 20:28	vote	accept	mathmo
Jan 17 at 14:13	history	edited	David White	CC BY-SA 4.0	Fixed typo; retagged
Jan 17 at 14:12	answer	added	David White		timeline score: 1
Jan 16 at 19:41	comment	added	Tyrone		The Warsaw circle. Every Quillen cofibrant space is a compactly generated normal Hausdorff space with CW homotopy type (the Warsaw circle fails the last property. The Sierpinski space, for instance, is not Hausdorff).
Jan 16 at 19:36	comment	added	Tyler Lawson		The Sierpinski two-point space is not cofibrant. There is an acyclic Serre fibration [0,1] -> S with no continuous section.
Jan 16 at 19:35	comment	added	mathmo		Thanks! Where can I find an explicit example of a non-cofibrant space?
Jan 16 at 18:43	comment	added	Tyrone		Any weakly contractible $X$ which is not cofibrant will do (if some $\ast\rightarrow X$ is a cofibration, then so is the composite $\emptyset\rightarrow\ast\rightarrow X$).
S Jan 16 at 18:37	review	First questions
Jan 17 at 0:37
S Jan 16 at 18:37	history	asked	mathmo	CC BY-SA 4.0