Is a function whose derivative vanishes at rationals constant?
112923
Let $f:\mathbb{R}\longrightarrow \mathbb{R}$ a differentiable function such that $f'(x)=0$ for all $x\in\mathbb{Q}$
5625
Entire function with vanishing derivatives?
130322
Show that $f(x) = 0$ if $x = 0$ $f(x) = \text{exp}(-1/x^{2})$ if $x \neq 0$ is infinitely differentiable but not analytic at $x_{0} = 0$ `
71799
A complex polynomial with partial derivatives equal to zero is constant.
141863
If the imaginary part of an entire function is never zero, the function is constant
69845
Construct a real function with is exactly $C^2$ such that its first derivative does not vanish everywhere
128719
Are constants the only continuous functions with "symmetric derivative" zero?
131485
Continuity of $\frac{x^3y^2}{x^4+y^4}$ at $(0,0)$?
139622
Generator of rational functions unchanged under $\sigma(X) = X + 1$
143874
Limit of derivative is zero. Does it imply a limit for f(x)?
114826
Zero Partials imply Constant Function Theorem or Proof
85480
Let $f(x,y)=\frac{x^3-y^3}{x^2+y^2}$. Is f differentiable in $(0,0)$?
16291
Discontinuous derivative.
152441
Vanishing of Taylor series coefficient
97371
Proving a function is constant, under certain conditions?
75932
Differentiability of $g:=f(\sqrt{x^2+y^2})$ for a $C^1$ function with $f'(0)=0$ NBHM $2008$
130180
Smooth function with all derivatives zero