Iterative fibonacci example proof#245
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Thanks for your contribution! Could you rebase and push again? I've just got some minor comments...
| text\<open>First, we define the mathematical Fibonacci function recursively. | ||
| Solution taken from: https://isabelle.in.tum.de/library/HOL/HOL-Number_Theory/Fib.html \<close> | ||
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| fun fib :: "nat \<Rightarrow> nat" where |
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nit: can you use cartouches instead of quotation marks, and match our prevailing style?
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| text\<open>Some basic properties of the mathematical definition\<close> | ||
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| lemma fib_plus_2: "fib (n + 2) = fib (n + 1) + fib n" |
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nit: can you phrase lemmas using assumes and shows and match our prevailing style?
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| text\<open>Lastly, prove that the iterative Fibonacci is correct with the mathematical definition.\<close> | ||
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| definition fib_correct_contract :: \<open>64 word \<Rightarrow> ('s, nat, 'b) function_contract\<close> where |
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Strictly speaking this is the only contract and functional correctness proof we need...
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Issue #6 : Implements one of the examples suggested (iterative Fibonacci correctness proof).
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