17 lines
438 B
Text
17 lines
438 B
Text
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inductive day :=
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monday, tuesday, wednesday, thursday, friday, saturday, sunday
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open day
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definition next_weekday : day → day,
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next_weekday monday := tuesday,
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next_weekday tuesday := wednesday,
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next_weekday wednesday := thursday,
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next_weekday thursday := friday,
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next_weekday friday := monday,
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next_weekday saturday := monday,
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next_weekday sunday := monday
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example : next_weekday (next_weekday monday) = wednesday :=
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rfl
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