How does one prove the following using natural deduction: $a ∧ ¬a \vdash b ∧ ¬b$
93707
Formal proof for $q \land \neg q \vdash r \land \neg r$
51369
Natural deduction proof of $p \lor (p\implies q)$ with propositional calculus
140194
Using natural deduction to prove that $p \implies q \vdash \lnot p \lor q$
154832
Show that there is always a proposition between two propositions logic
143627
Use the Fitch system to prove the tautology (p ∨ ¬p)
121720
Given ∃x.¬p(x), use the Fitch System to prove ¬∀x.p(x).
57215
Stuck on formal proofs. Not sure how to continue
140682
Proving a property of a Logic Formal Language
151038
How to prove (A v B), (A → C), (B → D) therefore (C v D)
105367
Proving $||\vec{a}+\vec{b}|| = ||\vec{a}-\vec{b}|| \iff \vec{a} \perp \vec{b}$
56191
How to demystify the axioms of propositional logic?
139841
Proving $A\setminus(B\setminus C)$ is not equal to $(A\setminus B)\setminus C$
42590
Understanding implication in logic truth tables (excerpt from textbook)
46939
Natural deduction, Proof $\vdash$ $P\Rightarrow(Q\Rightarrow P)$
93410
How to prove ~ (~P & ~Q) : P ∨ Q by natural deduction
140167
Proving $A+A'B=A+B$ without truth tables
6535
Proof of for-all / there-exists "negation"?