Understanding various nature (tautology, contradiction etc.) of assertions and their relations
136584
Understanding connection between terms tautology, contradiction, contingent, satisfiable, unsatisfiable, valid and invalid
68607
Could an argument with false Premises and a true Conclusion be logically valid?
155679
If union of two theories is not consistent one of them implies a sentence which the other implies opposite of it
108292
Precedence between implication and bi-implication
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?
31392
Examples and Counterexamples of Relations which Satisfy Certain Properties
115560
Exclusion in formation of comparative statements
52585
How to prove that $[(p \to q) \land (q \to r)] \to (p \to r)$ is a tautology without using the truth table?
105545
Confused about language and words in logic
135957
Why in an inconsistent axiom system every statement is true? (For Dummies)
70500
Implies ($\Rightarrow$) vs. Entails ($\models$) vs. Provable ($\vdash$)
97408
Interpreting having known
98386
First-order logic and second-order logic confusion
109685
An invalid argument, the conclusion of which is a tautology
101877
Assumed True until proven False. The Curious Case of the Vacuous Truth
147051
Soundness vs completeness, am I understanding? And proving soundness?
135267
Predicate Logic and Inference