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*Proposition:*

- Disjunction is
*commutative*: for all formulas`A`and`B``A`\/`B`iff`B`\/`A`. - Disjunction is
*associative*: for all formulas`A`,`B`, and`C`, we have`A`\/ (`B`\/`C`) iff (`A`\/`B`) \/`C`.

*Proof:* by truth tables.

Author: Wolfgang Schreiner

Last Modification: October 6, 1999