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Aug
19
answered Construction of a Hausdorff space from a topological space
Jul
26
answered Can any torsion free abelian group be embedded in a direct sum of copies of $\mathbb Q$?
Apr
16
answered Is vector subtraction commutative?
Apr
16
answered Lie bracket of vector fields and differential of diffeomorphism in its definition
Apr
16
answered There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
Apr
15
answered Does the gradient always point outward of a level surface?
Apr
15
asked There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
Mar
24
asked Does a diffeomorphism between the interiors of two manifolds extend to the manifolds?
Feb
21
answered Best Sets of Lecture Notes and Articles
Feb
5
asked The standard connection in a regular surface is symmetric
Feb
4
asked What does $ds^2$ mean and how does it specify a metric?
Jan
31
asked Is every compact hypersurface contained in a sphere which it touches twice?
Jan
31
answered Any compact embedded $2$-dimensional hypersurface in $\mathbb R^3$ has a point of positive Gaussian curvature
Jan
28
asked Does the gradient always point outward of a level surface?
Jan
20
asked If $\operatorname{dim} M > \operatorname{dim} N$, is there an injective smooth map $M\to N$?
Jan
17
asked When do regular values form an open set?
Jan
11
answered Dual notion of free module
Nov
30
answered $\mathrm{Spec}(R)\!=\!\mathrm{Max}(R)\!\cup\!\{0\}$ $\Rightarrow$ $R$ is a PID
Nov
24
answered Freyd-Mitchell's embedding theorem
Nov
24
asked Are fixed fields of finite subgroups generated by symmetric polynomials on Galois conjugates?