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Sep
20
answered Explaining what is Pathwise-connectedness.
Sep
18
answered Homeomorphic, homotopy equivalent and deformation retracts. How do I get a feeling for this?
Sep
16
answered What is the universal cover of a discrete set?
Sep
14
awarded  Fanatic
Sep
13
revised Obtaining Wirtinger presentation using van Kampen theorem
typo
Sep
13
answered Obtaining Wirtinger presentation using van Kampen theorem
Sep
12
comment Fundamental crossed square of a square of spaces
That looks right. You might find the following helpful: R. Steiner, Resolutions of spaces by n-cubes of fibrations, J. London Math. Soc. (2) 34 (1986) 169-176. You may need: "An introduction to homotopy theory and duality I" WH Cockroft, TM Jarvis - Bull. Soc. Math. Belgique, 1964
Sep
11
answered Fundamental crossed square of a square of spaces
Sep
6
answered Any relations between the weak topology on a Banach Space and the weak topology on CW complexes?
Sep
6
comment Maps from cogroups to groups & Eckmann-Hilton
Just a comment to say that you have to be working in the category of pointed spaces and homotopies respecting base point.
Sep
3
comment Identification of points versus line drawn between points
It does not matter if the line is inside or outside, the two are homeomorphic! Anyway, the map from the right hand picture to the left hand picture which collapses the outside bit is a homotopy equivalence, so induces an isomorphism of fundamental groups. They both have fundamental group the integers, as for the circle.
Sep
3
answered More elementary proof that $\pi_n(S^n) \cong \mathbb{Z}$
Sep
3
answered Identification of points versus line drawn between points
Sep
3
revised Suggestion about Algebraic Topology talk
gave another link
Aug
25
revised Isomorphism of Fundamental Groups (arcwise connected)
typos
Aug
24
answered Isomorphism of Fundamental Groups (arcwise connected)
Aug
18
comment The nature of isomorphism between fundamental groups with different base points
This question confirms my view that a lack of a groupoidal approach to 1-dimensional homotopy theory easily leads to confusion. This groupoid approach has been advocated by me since 1968, see my web pages.
Aug
16
answered Does the Wirtinger presentation extend to compliments of graphs and links?
Aug
15
revised Math and mental fatigue
soe additional points
Aug
15
answered Fundamental group of complement of circle with a line passing through it.