Is every closed set , the set of zeroes (resp.critical points) of some smooth real valued function?
130748
Infinitely differentiable function with given zero set?
58101
The set of points where two maps agree is closed?
128410
Showing that the set of fixed points is a smooth manifold
101281
Does there exist a smooth function which is nowhere analytic?
56983
Square of a function with an essential singularity
24050
Characterization of the Closure of a Set
150005
Existence of points in a differentiable function
60053
Does the boundary of an open set have measure zero (in $\mathbb{R}^n$)?
55679
Does there exist a continuous function from [0,1] to R that has uncountably many local maxima?
134199
Holomorphic function mapping a set onto a straight line
99678
Is a sphere a closed set?
11017
Does existence of partial derivatives implies continuity at a point $(x_0,y_0)$?
153107
Does every connected component of $\{z : |P(z)|<1 \}$ contain a zero?
106944
Is the set defined by y=sin(1/x) open or closed?
20688
Discontinuous functions with closed graphs
77624
Characterization of sets of differentiability
43419
At unique critical point, does local max imply global max?