1 let [pth_0g;pth_0l;pth_gg;pth_gl;pth_lg;pth_ll] =
3 (`((p = &0) ==> c > &0 ==> (c * p = &0)) /\
4 ((p = &0) ==> c < &0 ==> (c * p = &0)) /\
5 (p > &0 ==> c > &0 ==> c * p > &0) /\
6 (p > &0 ==> c < &0 ==> c * p < &0) /\
7 (p < &0 ==> c > &0 ==> c * p < &0) /\
8 (p < &0 ==> c < &0 ==> c * p > &0)`,
9 SIMP_TAC[REAL_MUL_RZERO] THEN
10 REWRITE_TAC[REAL_ARITH `(x > &0 <=> &0 < x) /\ (x < &0 <=> &0 < --x)`;
11 REAL_ARITH `~(p = &0) <=> p < &0 \/ p > &0`] THEN
12 REWRITE_TAC[IMP_IMP] THEN
13 REPEAT CONJ_TAC THEN DISCH_THEN(MP_TAC o MATCH_MP REAL_LT_MUL) THEN
16 let pth_nzg = prove_by_refinement(
17 `p <> &0 ==> c > &0 ==> c * p <> &0`,
20 REWRITE_TAC[NEQ;REAL_ENTIRE] THEN REAL_ARITH_TAC;
24 let pth_nzl = prove_by_refinement(
25 `p <> &0 ==> c < &0 ==> c * p <> &0`,
28 REWRITE_TAC[NEQ;REAL_ENTIRE] THEN REAL_ARITH_TAC;
32 let signs_lem01 = prove_by_refinement(
33 `c < &0 ==> p < &0 ==> (c * p = p') ==> p' > &0`,
36 ASM_MESON_TAC[REAL_MUL_LT;REAL_MUL_GT;real_gt];
40 let signs_lem02 = prove_by_refinement(
41 `c > &0 ==> p < &0 ==> (c * p = p') ==> p' < &0`,
44 ASM_MESON_TAC[REAL_MUL_LT;REAL_MUL_GT;real_gt];
48 let signs_lem03 = prove_by_refinement(
49 `c < &0 ==> p > &0 ==> (c * p = p') ==> p' < &0`,
52 ASM_MESON_TAC[REAL_MUL_LT;REAL_MUL_GT;real_gt];
56 let signs_lem04 = prove_by_refinement(
57 `c > &0 ==> p > &0 ==> (c * p = p') ==> p' > &0`,
60 ASM_MESON_TAC[REAL_MUL_LT;REAL_MUL_GT;real_gt];
64 let signs_lem05 = prove_by_refinement(
65 `c < &0 ==> (p = &0) ==> (c * p = p') ==> (p' = &0)`,
68 ASM_MESON_TAC[REAL_MUL_LT;REAL_MUL_GT;real_gt;REAL_MUL_RZERO];
72 let signs_lem06 = prove_by_refinement(
73 `c > &0 ==> (p = &0) ==> (c * p = p') ==> (p' = &0)`,
76 ASM_MESON_TAC[REAL_MUL_LT;REAL_MUL_GT;real_gt;REAL_MUL_RZERO];
80 let signs_lem07 = prove_by_refinement(
81 `c < &0 ==> p <> &0 ==> (c * p = p') ==> p' <> &0`,
85 ASM_MESON_TAC[NEQ;REAL_MUL_LT;REAL_MUL_GT;real_gt;REAL_MUL_RZERO;REAL_ENTIRE;REAL_GT_IMP_NZ];
90 let signs_lem08 = prove_by_refinement(
91 `c > &0 ==> p <> &0 ==> (c * p = p') ==> p' <> &0`,
95 ASM_MESON_TAC[NEQ;REAL_MUL_LT;REAL_MUL_GT;real_gt;REAL_MUL_RZERO;REAL_ENTIRE;REAL_LT_IMP_NZ];
100 let signs_lem002 = prove_by_refinement(
101 `!p. (p = &0) \/ (p <> &0)`,
108 let signs_lem003 = TAUT `a \/ b ==> (a ==> x) ==> (b ==> y) ==> (a /\ x \/ b /\ y)`;;
110 let sz_z_thm = ref TRUTH;;
111 let sz_nz_thm = ref TRUTH;;
113 let PULL_CASES_THM = prove
115 ((a = &0) /\ (p <=> p0) \/ (a <> &0) /\ (p <=> p1)) <=> ((p <=> (a = &0) /\ p0 \/ a <> &0 /\ p1 ))`,
117 REPEAT STRIP_TAC THEN REWRITE_TAC[NEQ] THEN MAP_EVERY BOOL_CASES_TAC [`p:bool`; `p0:bool`; `p1:bool`; `p2:bool`] THEN
118 ASM_REWRITE_TAC[] THEN REAL_ARITH_TAC);;
121 let signs_lem0002 = prove(
122 `!p. p <> &0 ==> (p > &0) \/ (p < &0)`,REWRITE_TAC [NEQ] THEN REAL_ARITH_TAC);;
123 let signs_lem0003 = TAUT `a \/ b ==> (a ==> x) ==> (b ==> y) ==> (a /\ x \/ b /\ y)`;;
125 let PULL_CASES_THM_NZ = prove
127 (a <> &0) ==> ((a > &0 /\ (p <=> p1) \/ a < &0 /\ (p <=> p2)) <=>
128 ((p <=> a > &0 /\ p1 \/ a < &0 /\ p2)))`,
130 REWRITE_TAC[NEQ] THEN
131 REPEAT STRIP_TAC THEN
132 REWRITE_TAC[NEQ] THEN
133 MAP_EVERY BOOL_CASES_TAC [`p:bool`; `p0:bool`; `p1:bool`; `p2:bool`] THEN
134 ASM_REWRITE_TAC[] THEN TRY (POP_ASSUM MP_TAC THEN REAL_ARITH_TAC)