when does $a\in\mathbb{R}$ does $\neg(a\leq 15\implies a>1)$ hold?
129824
For what $a \in \Bbb R$ does $\neg(3a>21\implies a \leq 5)$ hold?
56728
Question about limit points of a Subset of $\mathbb{R}$
73696
Given $(a_n)$ with $a_n \geq a_{n+1} \geq 0$ show that if $\sum \sqrt{a_n a_{n+1}} < \infty \implies \sum a_n < \infty$
63124
Show that $ \lVert A \rVert_2^2 \leq \lVert A \rVert _1 \lVert A \rVert _ \infty $
140759
What is exactly the difference between $\forall x \neg P(x)$ and $\neg \forall xP(x)$?
54791
Is it true or false that $\lvert P([0, 1]) \setminus P((0, 1)) \rvert > \lvert P(\mathbb{N}) \rvert$
45323
How to prove $\vdash\neg P\to (P\to Q)$?
48614
Why is "$P \Rightarrow Q$" equivalent to "$\neg Q \Rightarrow \neg P$"?
130297
$A$ be a subset of $[0,1]$ with non-empty interior ; then is it true that $\mathbb Q+A=\mathbb R$?
99782
$a_{n+1}=|a_n|-a_{n-1} \implies a_n \; \text{is periodic}$
36485
$H_n(X,A) \not \approx \tilde{H}_n(X/A)$
1117
Is there a bijection between $(0,1)$ and $\mathbb{R}$ that preserves rationality?
140194
Using natural deduction to prove that $p \implies q \vdash \lnot p \lor q$
52880
Intuition: If $a\leq b+\epsilon$ for all $\epsilon>0$ then $a\leq b$?
131596
Symmetric Inequality in $\mathbb{R}$
84251
Show that $\Gamma \cup \{\neg \phi\}$ is satisfiable if and only if $\Gamma\not \models \phi$
158498
$A\subset \mathbb{R}$ with more than one element and $A/ \{a\}$ is compact for a fixed $a\in A$