haftmann@16417
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theory Forward imports Primes begin
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paulson@10846
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paulson@10846
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text{*\noindent
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paulson@10846
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Forward proof material: of, OF, THEN, simplify, rule_format.
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paulson@10846
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*}
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paulson@10846
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paulson@10846
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text{*\noindent
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paulson@10846
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SKIP most developments...
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paulson@10846
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*}
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paulson@10846
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paulson@10846
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(** Commutativity **)
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paulson@10846
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paulson@10846
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lemma is_gcd_commute: "is_gcd k m n = is_gcd k n m"
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paulson@10958
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apply (auto simp add: is_gcd_def);
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paulson@10958
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done
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paulson@10846
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nipkow@25261
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lemma gcd_commute: "gcd m n = gcd n m"
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paulson@10958
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apply (rule is_gcd_unique)
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paulson@10958
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apply (rule is_gcd)
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paulson@10958
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apply (subst is_gcd_commute)
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paulson@10958
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apply (simp add: is_gcd)
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paulson@10958
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done
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paulson@10846
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nipkow@25261
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lemma gcd_1 [simp]: "gcd m (Suc 0) = Suc 0"
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paulson@10958
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apply simp
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paulson@10958
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done
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paulson@10846
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nipkow@25261
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lemma gcd_1_left [simp]: "gcd (Suc 0) m = Suc 0"
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wenzelm@11711
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apply (simp add: gcd_commute [of "Suc 0"])
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paulson@10958
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done
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paulson@10846
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paulson@10846
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text{*\noindent
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paulson@10846
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as far as HERE.
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paulson@10846
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*}
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paulson@10846
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paulson@10846
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text{*\noindent
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paulson@10846
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SKIP THIS PROOF
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paulson@10846
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*}
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paulson@10846
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nipkow@25261
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lemma gcd_mult_distrib2: "k * gcd m n = gcd (k*m) (k*n)"
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paulson@10846
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apply (induct_tac m n rule: gcd.induct)
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paulson@10846
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apply (case_tac "n=0")
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paulson@10958
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apply simp
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paulson@10846
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apply (case_tac "k=0")
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wenzelm@46488
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apply simp_all
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paulson@10846
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done
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paulson@10846
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paulson@10846
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text {*
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paulson@10846
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@{thm[display] gcd_mult_distrib2}
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paulson@10846
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\rulename{gcd_mult_distrib2}
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paulson@10846
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*};
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paulson@10846
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paulson@10846
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text{*\noindent
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paulson@10846
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of, simplified
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paulson@10846
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*}
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paulson@10846
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paulson@10846
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paulson@10846
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lemmas gcd_mult_0 = gcd_mult_distrib2 [of k 1];
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paulson@10846
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lemmas gcd_mult_1 = gcd_mult_0 [simplified];
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paulson@10846
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paulson@14403
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lemmas where1 = gcd_mult_distrib2 [where m=1]
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paulson@14403
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paulson@14403
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lemmas where2 = gcd_mult_distrib2 [where m=1 and k=1]
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paulson@14403
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paulson@14403
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lemmas where3 = gcd_mult_distrib2 [where m=1 and k="j+k"]
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paulson@14403
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paulson@10846
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text {*
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paulson@14403
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example using ``of'':
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paulson@10846
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@{thm[display] gcd_mult_distrib2 [of _ 1]}
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paulson@10846
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paulson@14403
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example using ``where'':
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paulson@14403
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@{thm[display] gcd_mult_distrib2 [where m=1]}
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paulson@14403
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paulson@14403
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example using ``where'', ``and'':
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paulson@14403
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@{thm[display] gcd_mult_distrib2 [where m=1 and k="j+k"]}
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paulson@14403
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paulson@10846
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@{thm[display] gcd_mult_0}
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paulson@10846
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\rulename{gcd_mult_0}
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paulson@10846
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paulson@10846
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@{thm[display] gcd_mult_1}
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paulson@10846
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\rulename{gcd_mult_1}
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paulson@10846
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paulson@10846
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@{thm[display] sym}
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paulson@10846
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\rulename{sym}
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paulson@10846
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*};
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paulson@10846
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paulson@13550
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lemmas gcd_mult0 = gcd_mult_1 [THEN sym];
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paulson@13550
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(*not quite right: we need ?k but this gives k*)
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paulson@10846
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paulson@13550
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lemmas gcd_mult0' = gcd_mult_distrib2 [of k 1, simplified, THEN sym];
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paulson@10846
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(*better in one step!*)
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paulson@10846
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paulson@10846
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text {*
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paulson@13550
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more legible, and variables properly generalized
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paulson@10846
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*};
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paulson@10846
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nipkow@25261
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lemma gcd_mult [simp]: "gcd k (k*n) = k"
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paulson@10846
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by (rule gcd_mult_distrib2 [of k 1, simplified, THEN sym])
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paulson@10846
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paulson@10846
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paulson@13550
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lemmas gcd_self0 = gcd_mult [of k 1, simplified];
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paulson@10846
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paulson@10846
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paulson@10846
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text {*
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paulson@25264
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@{thm[display] gcd_mult}
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paulson@25264
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\rulename{gcd_mult}
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paulson@25264
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paulson@25264
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@{thm[display] gcd_self0}
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paulson@25264
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\rulename{gcd_self0}
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paulson@25264
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*};
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paulson@25264
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paulson@25264
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text {*
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paulson@10846
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Rules handy with THEN
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paulson@10846
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paulson@10846
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@{thm[display] iffD1}
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paulson@10846
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\rulename{iffD1}
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paulson@10846
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paulson@10846
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@{thm[display] iffD2}
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paulson@10846
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\rulename{iffD2}
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paulson@10846
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*};
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paulson@10846
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paulson@10846
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paulson@10846
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text {*
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paulson@13550
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again: more legible, and variables properly generalized
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paulson@10846
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*};
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paulson@10846
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nipkow@25261
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lemma gcd_self [simp]: "gcd k k = k"
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paulson@10846
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by (rule gcd_mult [of k 1, simplified])
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paulson@10846
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paulson@10846
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paulson@10958
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text{*
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paulson@10958
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NEXT SECTION: Methods for Forward Proof
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paulson@10958
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paulson@10958
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NEW
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paulson@10958
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paulson@10958
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theorem arg_cong, useful in forward steps
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paulson@10958
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@{thm[display] arg_cong[no_vars]}
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paulson@10958
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\rulename{arg_cong}
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paulson@10958
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*}
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paulson@10958
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wenzelm@11711
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lemma "2 \<le> u \<Longrightarrow> u*m \<noteq> Suc(u*n)"
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wenzelm@12390
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apply (intro notI)
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paulson@10958
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txt{*
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paulson@10958
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before using arg_cong
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paulson@10958
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@{subgoals[display,indent=0,margin=65]}
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paulson@10958
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*};
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paulson@10958
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apply (drule_tac f="\<lambda>x. x mod u" in arg_cong)
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paulson@10958
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txt{*
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paulson@10958
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after using arg_cong
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paulson@10958
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@{subgoals[display,indent=0,margin=65]}
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paulson@10958
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*};
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paulson@10958
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apply (simp add: mod_Suc)
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paulson@10958
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done
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paulson@10958
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paulson@10958
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text{*
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paulson@10958
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have just used this rule:
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paulson@10958
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@{thm[display] mod_Suc[no_vars]}
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paulson@10958
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\rulename{mod_Suc}
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paulson@10958
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paulson@10958
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@{thm[display] mult_le_mono1[no_vars]}
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paulson@10958
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\rulename{mult_le_mono1}
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paulson@10958
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*}
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paulson@10958
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paulson@10958
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paulson@10958
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text{*
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paulson@10958
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example of "insert"
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paulson@10958
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*}
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paulson@10958
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paulson@10846
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lemma relprime_dvd_mult:
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nipkow@25261
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"\<lbrakk> gcd k n = 1; k dvd m*n \<rbrakk> \<Longrightarrow> k dvd m"
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paulson@10846
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apply (insert gcd_mult_distrib2 [of m k n])
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paulson@25264
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txt{*@{subgoals[display,indent=0,margin=65]}*}
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paulson@10958
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apply simp
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paulson@25264
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txt{*@{subgoals[display,indent=0,margin=65]}*}
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paulson@10846
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apply (erule_tac t="m" in ssubst);
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paulson@10958
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apply simp
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paulson@10846
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done
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paulson@10846
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paulson@10846
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paulson@10846
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text {*
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paulson@25264
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@{thm[display] relprime_dvd_mult}
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paulson@25264
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\rulename{relprime_dvd_mult}
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paulson@25264
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paulson@10846
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Another example of "insert"
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paulson@10846
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paulson@10846
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@{thm[display] mod_div_equality}
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paulson@10846
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\rulename{mod_div_equality}
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paulson@10846
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*};
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paulson@10846
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paulson@11407
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(*MOVED to Force.thy, which now depends only on Divides.thy
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paulson@11407
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lemma div_mult_self_is_m: "0<n \<Longrightarrow> (m*n) div n = (m::nat)"
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paulson@11407
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*)
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paulson@10846
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nipkow@25261
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lemma relprime_dvd_mult_iff: "gcd k n = 1 \<Longrightarrow> (k dvd m*n) = (k dvd m)";
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haftmann@27658
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by (auto intro: relprime_dvd_mult elim: dvdE)
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paulson@10846
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nipkow@25261
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lemma relprime_20_81: "gcd 20 81 = 1";
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paulson@10846
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by (simp add: gcd.simps)
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paulson@10846
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paulson@10846
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text {*
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paulson@10846
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Examples of 'OF'
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paulson@10846
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paulson@10846
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@{thm[display] relprime_dvd_mult}
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paulson@10846
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\rulename{relprime_dvd_mult}
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paulson@10846
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paulson@10846
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@{thm[display] relprime_dvd_mult [OF relprime_20_81]}
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paulson@10846
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paulson@10846
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@{thm[display] dvd_refl}
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paulson@10846
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\rulename{dvd_refl}
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paulson@10846
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paulson@10846
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@{thm[display] dvd_add}
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paulson@10846
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\rulename{dvd_add}
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paulson@10846
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paulson@10846
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@{thm[display] dvd_add [OF dvd_refl dvd_refl]}
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paulson@10846
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paulson@10846
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@{thm[display] dvd_add [OF _ dvd_refl]}
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paulson@10846
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*};
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paulson@10846
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wenzelm@11711
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lemma "\<lbrakk>(z::int) < 37; 66 < 2*z; z*z \<noteq> 1225; Q(34); Q(36)\<rbrakk> \<Longrightarrow> Q(z)";
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wenzelm@11711
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apply (subgoal_tac "z = 34 \<or> z = 36")
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paulson@10958
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txt{*
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paulson@10958
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the tactic leaves two subgoals:
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paulson@10958
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@{subgoals[display,indent=0,margin=65]}
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paulson@10958
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*};
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paulson@10846
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apply blast
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wenzelm@11711
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apply (subgoal_tac "z \<noteq> 35")
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paulson@10958
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txt{*
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paulson@10958
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the tactic leaves two subgoals:
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paulson@10958
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@{subgoals[display,indent=0,margin=65]}
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paulson@10958
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*};
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paulson@10846
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apply arith
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paulson@10846
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apply force
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paulson@10846
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done
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paulson@10846
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paulson@10846
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paulson@10846
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end
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