deduction for propositonal logic
124424
How to show that there is a deduction of $\varphi\leftrightarrow\psi$
32950
Fake induction proofs
43655
Verify is tautology by using logical equivalence
75381
How can we reason about "if P then Q" or "P only if Q" statements in propositional logic?
148237
Is ¬¬(¬¬P → P) provable in intuitionistic logic?
158016
Help understanding predicate logic question/proof
5293
Show that the logic $ \ \forall x \exists y \ P(x,y) \ $ is not logically equivalent to $ \ \exists x \forall y \ P(x,y) \ $
94617
Showing Consistency and Completeness implies a unique truth assignment
103463
Mantel's Theorem proof verification
16187
proof of functional completeness of logical operators
114550
Well-ordering theorem and second-order logic
72185
The negation of a limit condition, Spivak style.
139064
Show by using logical connectives laws that $(P\to Q) \land (Q \to R) $ is equivalent to $(P \to R) \land [(P \iff Q) \lor (R \iff Q)]$
111862
Proof for sequent (Logic)
53199
First-Order Logic: Formalisation of the phrase "Not all that glitters is gold"
104771
Dedekind's cut and axioms
72034
Truth table and the meaning of $\oplus$ in propositional logic