How do I prove ~(A & B) therefore ~A V ~B using natural deduction?
93410
How to prove ~ (~P & ~Q) : P ∨ Q by natural deduction
32244
Propositional Logic - Deduction
124424
How to show that there is a deduction of $\varphi\leftrightarrow\psi$
32402
$(A \implies B) \implies (\neg B \implies \neg A)$?
134588
Seeking a direct proof about nested inclusions
142168
can we a prove ⊢ (α → α) → (α → α)
104124
Prove or disprove: $A-(B-C) = (A-B)-C$
77759
How do i prove that $(p \vee q) \wedge (\neg p \vee r) \rightarrow (q \vee r)$ is a tautology without using the truth table?
61066
Prove: $(A\rightarrow B),(A\rightarrow C)\rightarrow B, \mapsto_{HPC} B $
33542
When is $A- B = B- A$?
116978
Trying to prove $p,p \to (r \to q) \vdash (\neg q \to \neg r)$ by using natural deduction.
65379
Deriving $\neg R$ from $\{R↔(R∨(P∧¬P)), R↔¬P, ¬P→(P↔(Q→Q)), P→Q\}$
20346
'Algebraic' way to prove the boolean identity $a + \overline{a}*b = a + b$
120292
How to formally prove: if $d\mid da+b$, then $d\mid b$?
107383
Derived sets - prove $(A \cup B)' = A' \cup B'$
138212
Please help me prove: $v(a+b)\leq v(a)+v(b)$, and $v(ab)\leq v(a)v(b)$ where $v(x)=\inf{\{\vert x^n \vert}^{1/n}: n\in\mathbb{N}\}$
151356
Need Hints Prove "$((\neg \alpha \to \alpha) \to \alpha) $" Using Axiom 1,2,3 and MP and deduction theorem