From: Cristian Armentano Date: Tue, 11 Sep 2007 14:25:35 +0000 (+0000) Subject: some theorem names changed. X-Git-Tag: 0.4.95@7852~175 X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=commitdiff_plain;h=941dbcc41a8f6f77336b2e999372dccef7dd00fc;p=helm.git some theorem names changed. --- diff --git a/matita/library/nat/gcd_properties1.ma b/matita/library/nat/gcd_properties1.ma index 94aa67670..535e7b42a 100644 --- a/matita/library/nat/gcd_properties1.ma +++ b/matita/library/nat/gcd_properties1.ma @@ -157,17 +157,6 @@ apply (leb_elim n m) ] qed. -(* a basic property of divides predicate *) - -theorem O_div_c_to_c_eq_O: \forall c:nat. -O \divides c \to c = O. -intros. -apply antisymmetric_divides -[ apply divides_n_O -| assumption -] -qed. - (* an alternative characterization for gcd *) theorem gcd1: \forall a,b,c:nat. c \divides a \to c \divides b \to @@ -187,7 +176,7 @@ elim (H2 ((gcd a b))) qed. -theorem eq_gcd_times_times_eqv_times_gcd: \forall a,b,c:nat. +theorem eq_gcd_times_times_times_gcd: \forall a,b,c:nat. (gcd (c*a) (c*b)) = c*(gcd a b). intros. apply (nat_case1 c) @@ -249,7 +238,7 @@ apply gcd1 ] qed. -theorem aDIVIDES_b_TIMES_c_to_GCD_a_b_eq_d_to_aDIVd_DIVIDES_c: \forall a,b,c,d:nat. +theorem divides_times_to_gcd_to_divides_div: \forall a,b,c,d:nat. a \divides (b*c) \to (gcd a b) = d \to (a/d) \divides c. intros. apply (nat_case1 a) @@ -276,7 +265,10 @@ apply (nat_case1 a) | apply (lt_times_eq_O b c) [ rewrite > H3. apply lt_O_S - | apply (O_div_c_to_c_eq_O (b*c) H) + | apply antisymmetric_divides + [ apply divides_n_O + | assumption + ] ] ] | rewrite < H1. @@ -301,7 +293,7 @@ apply (nat_case1 a) assumption | apply (inj_times_r1 d ? ?) [ assumption - | rewrite < (eq_gcd_times_times_eqv_times_gcd (a/d) (b/d) d). + | rewrite < (eq_gcd_times_times_times_gcd (a/d) (b/d) d). rewrite < (times_n_SO d). rewrite < (sym_times (a/d) d). rewrite < (sym_times (b/d) d). @@ -350,57 +342,46 @@ apply (nat_case1 a) ] qed. -theorem gcd_sum_times_eq_gcd_aux: \forall a,b,d,m:nat. -(gcd (a+m*b) b) = d \to (gcd a b) = d. +theorem gcd_plus_times_gcd: \forall a,b,d,m:nat. +(gcd (a+m*b) b) = (gcd a b). intros. apply gcd1 -[ rewrite > (minus_plus_m_m a (m*b)). - apply divides_minus - [ rewrite < H. - apply divides_gcd_n - | rewrite > (times_n_SO d). - rewrite > (sym_times d ?). - apply divides_times - [ apply divides_SO_n - | rewrite < H. - apply divides_gcd_m +[ apply divides_plus + [ apply divides_gcd_n + | apply (trans_divides ? b ?) + [ apply divides_gcd_m + | rewrite > sym_times. + apply (witness b (b*m) m). + reflexivity ] ] -| rewrite < H. - apply divides_gcd_m +| apply divides_gcd_m | intros. - rewrite < H. apply divides_d_gcd [ assumption - | apply divides_plus + | rewrite > (minus_plus_m_m a (m*b)). + apply divides_minus [ assumption - | rewrite > (times_n_SO d1). - rewrite > (sym_times d1 ?). - apply divides_times - [ apply divides_SO_n - | assumption - ] + | apply (trans_divides ? b ?) + [ assumption + | rewrite > sym_times. + apply (witness b (b*m) m). + reflexivity + ] ] ] ] qed. -theorem gcd_sum_times_eq_gcd: \forall a,b,m:nat. -(gcd (a+m*b) b) = (gcd a b). -intros. -apply sym_eq. -apply (gcd_sum_times_eq_gcd_aux a b (gcd (a+m*b) b) m). -reflexivity. -qed. -theorem gcd_div_div_eq_div_gcd: \forall a,b,m:nat. +theorem eq_gcd_div_div_div_gcd: \forall a,b,m:nat. O \lt m \to m \divides a \to m \divides b \to (gcd (a/m) (b/m)) = (gcd a b) / m. intros. apply (inj_times_r1 m H). rewrite > (sym_times m ((gcd a b)/m)). rewrite > (NdivM_times_M_to_N (gcd a b) m) -[ rewrite < eq_gcd_times_times_eqv_times_gcd. +[ rewrite < eq_gcd_times_times_times_gcd. rewrite > (sym_times m (a/m)). rewrite > (sym_times m (b/m)). rewrite > (NdivM_times_M_to_N a m H H1). @@ -413,7 +394,7 @@ rewrite > (NdivM_times_M_to_N (gcd a b) m) qed. -theorem gcdSO_divides_divides_times_divides: \forall c,e,f:nat. +theorem gcd_SO_to_divides_to_divides_to_divides_times: \forall c,e,f:nat. (gcd e f) = (S O) \to e \divides c \to f \divides c \to (e*f) \divides c. intros. @@ -462,13 +443,13 @@ qed. the following sense: if a1 and a2 are relatively prime, then gcd(a1·a2, b) = gcd(a1, b)·gcd(a2, b). *) -theorem gcd_aTIMESb_c_eq_gcd_a_c_TIMES_gcd_b_c: \forall a,b,c:nat. +theorem gcd_SO_to_eq_gcd_times_times_gcd_gcd: \forall a,b,c:nat. (gcd a b) = (S O) \to (gcd (a*b) c) = (gcd a c) * (gcd b c). intros. apply gcd1 [ apply divides_times; apply divides_gcd_n -| apply (gcdSO_divides_divides_times_divides c (gcd a c) (gcd b c)) +| apply (gcd_SO_to_divides_to_divides_to_divides_times c (gcd a c) (gcd b c)) [ apply gcd1 [ apply divides_SO_n | apply divides_SO_n @@ -492,11 +473,11 @@ apply gcd1 | apply (divides_gcd_m) ] | intros. - rewrite < (eq_gcd_times_times_eqv_times_gcd b c (gcd a c)). + rewrite < (eq_gcd_times_times_times_gcd b c (gcd a c)). rewrite > (sym_times (gcd a c) b). rewrite > (sym_times (gcd a c) c). - rewrite < (eq_gcd_times_times_eqv_times_gcd a c b). - rewrite < (eq_gcd_times_times_eqv_times_gcd a c c). + rewrite < (eq_gcd_times_times_times_gcd a c b). + rewrite < (eq_gcd_times_times_times_gcd a c c). apply (divides_d_gcd) [ apply (divides_d_gcd) [ rewrite > (times_n_SO d). @@ -525,7 +506,7 @@ apply gcd1 qed. -theorem gcd_eq_gcd_minus: \forall a,b:nat. +theorem eq_gcd_gcd_minus: \forall a,b:nat. a \lt b \to (gcd a b) = (gcd (b - a) b). intros. apply sym_eq.