12 lines
273 B
Text
12 lines
273 B
Text
#lang lean4
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def f : Nat → Nat → Nat
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| 0, b => b+1
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| a+1, b => f a (f a b)
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theorem ex1 (b) : f 0 b = b+1 := rfl
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theorem ex2 (b) : f 1 b = (b+1)+1 := rfl
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theorem ex3 (b) : f 2 b = b+1+1+1+1 := rfl
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theorem ex4 (a b) : f (a+1) b = f a (f a b) := rfl
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#eval f 2 5
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