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-rw-r--r--consecutive-fibonacci-numbers-are-coprime.lisp6
1 files changed, 6 insertions, 0 deletions
diff --git a/consecutive-fibonacci-numbers-are-coprime.lisp b/consecutive-fibonacci-numbers-are-coprime.lisp
index 482eb65..e9bc9e2 100644
--- a/consecutive-fibonacci-numbers-are-coprime.lisp
+++ b/consecutive-fibonacci-numbers-are-coprime.lisp
@@ -25,6 +25,12 @@
((< n m) (gcd$ (- m n) n))
(t (gcd$ (- n m) m))))
+;; gcd$ の結果は正の整数である
+(defthm posp-gcd$
+ (implies (and (posp m)
+ (posp n))
+ (posp (gcd$ m n))))
+
;; n と m が互いに素かどうかを調べる述語
(defmacro coprimep (n m)
`(equal (gcd$ ,n ,m) 1))