Associativity
This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.
State
(p ∨ q) ∨ r :: p ∨ (q ∨ r), and likewise for ·.
Show
Regrouping within the same connective is free.
Watch for
Same connective only. Regrouping across a mixed formula needs Distribution — next video.