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4. Formal Logic / D. Modal Logic ML / 6. Temporal Logic

[Inferences across past, present and future]

3 ideas
With four tense operators, all complex tenses reduce to fourteen basic cases [Burgess]
F: will sometime, P: was sometime, G: will always, H: was always [Fitting/Mendelsohn]
We can treat modal worlds as different times [Sider]