Absorption Laws (Logic)/Conjunction Absorbs Disjunction/Proof 2

From ProofWiki
Jump to navigation Jump to search

Theorem

$p \land \paren {p \lor q} \dashv \vdash p$


Proof

By calculation:

\(\ds p \land \paren {p \lor q}\) \(=\) \(\ds \paren {p \lor \bot} \land \paren {p \lor q}\) Disjunction with Contradiction
\(\ds \) \(=\) \(\ds p \lor \paren {\bot \land q}\) Disjunction is Left Distributive over Conjunction
\(\ds \) \(=\) \(\ds p \lor \bot\) Conjunction with Contradiction
\(\ds \) \(=\) \(\ds p\) Disjunction with Contradiction

$\blacksquare$