Chapter 8 of “Specifying Systems” often makes a distinction between an action and a temporal formula, but I’m having trouble finding any definitions earlier the book that tell me what the difference is. Is it this?: actions are ordinary formulas with primed variables and/or ENABLED, and temporal formulas also permit [] and <>.
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"[]<>(<<A>>_v \/ <<B>>_v) isn't a TLA formula."
Chapter 8 of “Specifying Systems” often makes a distinction between an action and a temporal formula, but I’m having trouble finding any definitions earlier the book that tell me what the difference is. Is it this?: actions are ordinary formulas with primed variables and/or ENABLED, and temporal formulas also permit [] and <>.
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Section 16.2.4 gives a syntactic definition of a valid TLA formula, which is defined inductively from a few base rules. Since []<>(<<A>>_v \/ <<B>>_v) cannot be built from those rules, it's not a valid TLA formula, even though it's a temporal formula. But you can construct []<><<A \/ B>>_v, which is logically equivalent.
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