Tyler Lawson's user avatar
Tyler Lawson's user avatar
Tyler Lawson's user avatar
Tyler Lawson
  • Member for 14 years, 5 months
  • Last seen this week
28 votes

Fundamental group of the line with the double origin.

27 votes
Accepted

vector bundle trivial over every compact subset, then it is globally trivial

26 votes

What is a square root of a line bundle?

26 votes

What are some toy models for the stable homotopy groups of spheres?

25 votes
Accepted

Idempotent ring spectrum

25 votes
Accepted

Eilenberg-Mac lane spaces and a generalization

25 votes

When does homology represent an embedded sphere?

24 votes
Accepted

can a common mortal understand why the affine line is not smooth in brave new algebraic geometry?

24 votes
Accepted

Why is homology not (co)representable?

23 votes
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Cech to derived spectral sequence and sheafification

23 votes

What are the uses of the homotopy groups of spheres?

23 votes
Accepted

Čech cohomology is isomorphic to singular cohomology

22 votes

Do we still need models of spectra other than the $\infty$-category $\mathrm{Sp}$?

22 votes

Stable homotopy category and the moduli space of formal groups

21 votes
Accepted

Homology theory constructed in a homotopy-invariant way

21 votes

What kind of geometric operations "scale up" cohomology?

20 votes
Accepted

Subgroups of free abelian groups are free: a topological proof?

20 votes

Why does one think to Steenrod squares and powers?

20 votes
Accepted

What facts in commutative algebra fail miserably for simplicial commutative rings, even up to homotopy?

20 votes
Accepted

Different way to view action of fundamental group on higher homotopy groups

20 votes
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Pullback and homology

20 votes
Accepted

Concrete Examples of Shimura Surfaces

19 votes

Is there a "simplification" functor in algebraic topology?

19 votes

Why are free groups residually finite?

19 votes
Accepted

Are the homology and cohomology Serre spectral sequences dual to each other?

19 votes

Intuition about the cotangent complex?

19 votes
Accepted

Why does elliptic cohomology fail to be unique up to contractible choice?

18 votes

Describing the universal covering map for the twice punctured complex plane

18 votes
Accepted

Why is the standard definition of cocycle the one that _always_ comes up??

18 votes

Why is the standard definition of cocycle the one that _always_ comes up??

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