19 lines
270 B
Text
19 lines
270 B
Text
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open nat
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definition fib : nat → nat,
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fib 0 := 1,
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fib 1 := 1,
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fib (x+2) := fib x + fib (x+1)
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theorem fib0 : fib 0 = 1 :=
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rfl
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theorem fib1 : fib 1 = 1 :=
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rfl
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theorem fib_succ_succ (a : nat) : fib (a+2) = fib a + fib (a+1) :=
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rfl
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example : fib 8 = 34 :=
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rfl
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