New posts in algebraic-topology

Is there a domain in $\mathbb{R}^3$ with finite non-trivial $\pi_1$ but $H_1=0$?

Homotopy groups of $\mathbb{RP}^\infty$, $\mathbb{CP}^\infty$.

If $f\!: X\simeq Y$, then $X\!\cup_\varphi\!\mathbb{B}^k \simeq Y\!\cup_{f\circ\varphi}\!\mathbb{B}^k$.

Why every smooth orientable 4-dimensional manifold admits an immersion into $\mathbb{R}^{6}$?

Good textbook or lecture notes on Seiberg-Witten theory.

Is it possible for a closed manifold to deformation retract onto a proper subset of itself?

The image of simply-connected domain

What is combinatorial homotopy theory?

$I^2$ does not retract into comb space

Can we simultaneously realize arbitrary homotopy groups and arbitrary homology groups?

Homology of the Klein Bottle

A manifold with $\pi_1 = \pi_2 = \pi_4 = 0, \pi_3 = \mathbb{Z}$

Amalgamated product $\mathbb{Z}*_{\mathbb{Z}} 0$

Homology of $S^1 \times (S^1 \vee S^1)$

Fundamental group of the product of 3-tori minus the diagonal

Why $\mathbb{D}^2 / \mathbb{S}^1 = \mathbb{S}^2$? [duplicate]

Good book on homology

Why are we interested in cohomology?

What is wrong with the following argument about splitting an exact sequence of abelian groups?

Cohomology ring of $H^*(A_5;\mathbb Z_2)$?