Propositional Logic: $Τ\vDash\varphi\implies\existsΤ_0\subseteq T$ such that $Τ_0\vDash\varphi$
125966
Why there's a finite $\Gamma '$ such that $\Gamma ' \vDash \varphi$?
35236
Proof $p \vdash q \Rightarrow p$
153634
A statment about the equivalence between the Axiom of Choice and the surjectivity of the projections.
55461
How to prove that if $a$ belongs to $\mathbb R$, such that $0\leq a \leq\epsilon$, then $a = 0$
106670
Existence of vector space complement and axiom of choice
144266
set theory proof of $A\cap B = A \setminus(A\setminus B)$
118189
Proving the pairing axiom from the rest of ZF
42590
Understanding implication in logic truth tables (excerpt from textbook)
101741
Selection of logical connectives {¬,∨,∧,⇒,⇔} in set theory?
91861
Propositional Logic: p → q, ¬p → r, ¬q → ¬r ⊢ q
93707
Formal proof for $q \land \neg q \vdash r \land \neg r$
154832
Show that there is always a proposition between two propositions logic
84251
Show that $\Gamma \cup \{\neg \phi\}$ is satisfiable if and only if $\Gamma\not \models \phi$
17624
Axiom of Choice iff Every set has a choice function
42095
Existence in ZF of a set with countable power set
5313
Existence of how many sets is asserted by the axiom of choice in this case?
12539
Set Theory: Equivalency of Axiom of Choice and Choice Function