/
arithmeticScript.sml
4253 lines (3756 loc) · 165 KB
/
arithmeticScript.sml
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(* ===================================================================== *)
(* FILE : arithmeticScript.sml *)
(* DESCRIPTION : Definitions and properties of +,-,*,EXP, <=, >=, etc. *)
(* Translated from hol88. *)
(* *)
(* AUTHORS : (c) Mike Gordon and *)
(* Tom Melham, University of Cambridge *)
(* DATE : 88.04.02 *)
(* TRANSLATOR : Konrad Slind, University of Calgary *)
(* DATE : September 15, 1991 *)
(* ADDITIONS : December 22, 1992 *)
(* ===================================================================== *)
structure arithmeticScript =
struct
(* interactive use:
app load ["prim_recTheory", "Q", "metisLib", "boolSimps", "SatisfySimps"];
*)
open HolKernel boolLib Parse
Prim_rec simpLib boolSimps metisLib BasicProvers;
local
open OpenTheoryMap
val ns = ["Number", "Natural"]
in
fun ot0 x y = OpenTheory_const_name
{const = {Thy = "arithmetic", Name = x}, name = (ns, y)}
fun ot x = ot0 x x
fun otunwanted x = OpenTheory_const_name
{const = {Thy = "arithmetic", Name = x},
name = (["Unwanted"], "id")}
end
val _ = new_theory "arithmetic";
val _ = if !Globals.interactive then () else Feedback.emit_WARNING := false;
val NOT_SUC = numTheory.NOT_SUC
and INV_SUC = numTheory.INV_SUC
and INDUCTION = numTheory.INDUCTION;
val num_Axiom = prim_recTheory.num_Axiom;
val INV_SUC_EQ = prim_recTheory.INV_SUC_EQ
and LESS_REFL = prim_recTheory.LESS_REFL
and SUC_LESS = prim_recTheory.SUC_LESS
and NOT_LESS_0 = prim_recTheory.NOT_LESS_0
and LESS_MONO = prim_recTheory.LESS_MONO
and LESS_SUC_REFL = prim_recTheory.LESS_SUC_REFL
and LESS_SUC = prim_recTheory.LESS_SUC
and LESS_THM = prim_recTheory.LESS_THM
and LESS_SUC_IMP = prim_recTheory.LESS_SUC_IMP
and LESS_0 = prim_recTheory.LESS_0
and EQ_LESS = prim_recTheory.EQ_LESS
and SUC_ID = prim_recTheory.SUC_ID
and NOT_LESS_EQ = prim_recTheory.NOT_LESS_EQ
and LESS_NOT_EQ = prim_recTheory.LESS_NOT_EQ
and LESS_SUC_SUC = prim_recTheory.LESS_SUC_SUC
and PRE = prim_recTheory.PRE
and RTC_IM_TC = prim_recTheory.RTC_IM_TC
and TC_IM_RTC_SUC = prim_recTheory.TC_IM_RTC_SUC
and LESS_ALT = prim_recTheory.LESS_ALT;
(*---------------------------------------------------------------------------*
* The basic arithmetic operations. *
*---------------------------------------------------------------------------*)
val ADD = new_recursive_definition
{name = "ADD",
rec_axiom = num_Axiom,
def = ``($+ 0 n = n) /\
($+ (SUC m) n = SUC ($+ m n))``};
val _ = set_fixity "+" (Infixl 500);
val _ = ot "+"
(*---------------------------------------------------------------------------*
* Define NUMERAL, a tag put on numeric literals, and the basic constructors *
* of the "numeral type". *
*---------------------------------------------------------------------------*)
val NUMERAL_DEF = new_definition("NUMERAL_DEF", ``NUMERAL (x:num) = x``);
val ALT_ZERO = new_definition("ALT_ZERO", ``ZERO = 0``);
local
open OpenTheoryMap
in
val _ = OpenTheory_const_name {const = {Thy = "arithmetic", Name = "ZERO"},
name = (["Number", "Natural"], "zero")}
val _ = OpenTheory_const_name {const = {Thy = "num", Name = "0"},
name=(["Number", "Natural"], "zero")}
end
val BIT1 = new_definition("BIT1", ``BIT1 n = n + (n + SUC 0)``);
val BIT2 = new_definition("BIT2", ``BIT2 n = n + (n + SUC (SUC 0))``);
val _ = new_definition(
GrammarSpecials.nat_elim_term,
``^(mk_var(GrammarSpecials.nat_elim_term, Type`:num->num`)) n = n``);
val _ = otunwanted "NUMERAL"
val _ = ot0 "BIT1" "bit1"
val _ = ot0 "BIT2" "bit2"
(*---------------------------------------------------------------------------*
* After this call, numerals parse into `NUMERAL( ... )` *
*---------------------------------------------------------------------------*)
val _ = add_numeral_form (#"n", NONE);
val _ = set_fixity "-" (Infixl 500);
val _ = Unicode.unicode_version {u = UTF8.chr 0x2212, tmnm = "-"};
val _ = TeX_notation {hol = UTF8.chr 0x2212, TeX = ("\\ensuremath{-}", 1)}
val SUB = new_recursive_definition
{name = "SUB",
rec_axiom = num_Axiom,
def = ``(0 - m = 0) /\
(SUC m - n = if m < n then 0 else SUC(m - n))``};
val _ = ot "-"
(* Also add concrete syntax for unary negation so that future numeric types
can use it. We can't do anything useful with it for the natural numbers
of course, but it seems like this is the best ancestral place for it.
Descendents wanting to use this will include at least
integer, real, words, rat
*)
val _ = add_rule { term_name = "numeric_negate",
fixity = Prefix 900,
pp_elements = [TOK "-"],
paren_style = OnlyIfNecessary,
block_style = (AroundEachPhrase, (PP.CONSISTENT,0))};
(* Similarly, add syntax for the injection from nats symbol (&). This isn't
required in this theory, but will be used by descendents. *)
val _ = add_rule {term_name = GrammarSpecials.num_injection,
fixity = Prefix 900,
pp_elements = [TOK GrammarSpecials.num_injection],
paren_style = OnlyIfNecessary,
block_style = (AroundEachPhrase, (PP.CONSISTENT,0))};
(* overload it to the nat_elim term *)
val _ = overload_on (GrammarSpecials.num_injection,
mk_const(GrammarSpecials.nat_elim_term, ``:num -> num``))
val _ = set_fixity "*" (Infixl 600);
val _ = TeX_notation {hol = "*", TeX = ("\\HOLTokenProd{}", 1)}
val MULT = new_recursive_definition
{name = "MULT",
rec_axiom = num_Axiom,
def = ``(0 * n = 0) /\
(SUC m * n = (m * n) + n)``};
val _ = ot "*"
val EXP = new_recursive_definition
{name = "EXP",
rec_axiom = num_Axiom,
def = ``($EXP m 0 = 1) /\
($EXP m (SUC n) = m * ($EXP m n))``};
val _ = ot0 "EXP" "^"
val _ = set_fixity "EXP" (Infixr 700);
val _ = add_infix("**", 700, HOLgrammars.RIGHT);
val _ = overload_on ("**", Term`$EXP`);
val _ = TeX_notation {hol = "**", TeX = ("\\HOLTokenExp{}", 2)}
(* special-case squares and cubes *)
val _ = add_rule {fixity = Suffix 2100,
term_name = UnicodeChars.sup_2,
block_style = (AroundEachPhrase,(PP.CONSISTENT, 0)),
paren_style = OnlyIfNecessary,
pp_elements = [TOK UnicodeChars.sup_2]}
val _ = overload_on (UnicodeChars.sup_2, ``\x. x ** 2``)
val _ = add_rule {fixity = Suffix 2100,
term_name = UnicodeChars.sup_3,
block_style = (AroundEachPhrase,(PP.CONSISTENT, 0)),
paren_style = OnlyIfNecessary,
pp_elements = [TOK UnicodeChars.sup_3]}
val _ = overload_on (UnicodeChars.sup_3, ``\x. x ** 3``)
val GREATER_DEF = new_definition("GREATER_DEF", ``$> m n = n < m``)
val _ = set_fixity ">" (Infix(NONASSOC, 450))
val _ = TeX_notation {hol = ">", TeX = ("\\HOLTokenGt{}", 1)}
val _ = ot ">"
val LESS_OR_EQ = new_definition ("LESS_OR_EQ", ``$<= m n = m < n \/ (m = n)``)
val _ = set_fixity "<=" (Infix(NONASSOC, 450))
val _ = Unicode.unicode_version { u = Unicode.UChar.leq, tmnm = "<="}
val _ = TeX_notation {hol = Unicode.UChar.leq, TeX = ("\\HOLTokenLeq{}", 1)}
val _ = TeX_notation {hol = "<=", TeX = ("\\HOLTokenLeq{}", 1)}
val _ = ot "<="
val GREATER_OR_EQ =
new_definition("GREATER_OR_EQ", ``$>= m n = m > n \/ (m = n)``)
val _ = set_fixity ">=" (Infix(NONASSOC, 450))
val _ = Unicode.unicode_version { u = Unicode.UChar.geq, tmnm = ">="};
val _ = TeX_notation {hol = ">=", TeX = ("\\HOLTokenGeq{}", 1)}
val _ = TeX_notation {hol = Unicode.UChar.geq, TeX = ("\\HOLTokenGeq{}", 1)}
val _ = ot ">="
val EVEN = new_recursive_definition
{name = "EVEN",
rec_axiom = num_Axiom,
def = ``(EVEN 0 = T) /\
(EVEN (SUC n) = ~EVEN n)``};
val _ = ot0 "EVEN" "even"
val ODD = new_recursive_definition
{name = "ODD",
rec_axiom = num_Axiom,
def = ``(ODD 0 = F) /\
(ODD (SUC n) = ~ODD n)``};
val _ = ot0 "ODD" "odd"
val [num_case_def] = Prim_rec.define_case_constant num_Axiom
val FUNPOW = new_recursive_definition
{name = "FUNPOW",
rec_axiom = num_Axiom,
def = ``(FUNPOW f 0 x = x) /\
(FUNPOW f (SUC n) x = FUNPOW f n (f x))``};
val NRC = new_recursive_definition {
name = "NRC",
rec_axiom = num_Axiom,
def = ``(NRC R 0 x y = (x = y)) /\
(NRC R (SUC n) x y = ?z. R x z /\ NRC R n z y)``};
val _ = overload_on ("RELPOW", ``NRC``)
val _ = overload_on ("NRC", ``NRC``)
(*---------------------------------------------------------------------------
THEOREMS
---------------------------------------------------------------------------*)
val ONE = store_thm ("ONE", ``1 = SUC 0``,
REWRITE_TAC [NUMERAL_DEF, BIT1, ALT_ZERO, ADD]);
val TWO = store_thm ("TWO", ``2 = SUC 1``,
REWRITE_TAC [NUMERAL_DEF, BIT2, ONE, ADD, ALT_ZERO,BIT1]);
val NORM_0 = store_thm ("NORM_0", ``NUMERAL ZERO = 0``,
REWRITE_TAC [NUMERAL_DEF, ALT_ZERO]);
fun INDUCT_TAC g = INDUCT_THEN INDUCTION ASSUME_TAC g;
val EQ_SYM_EQ' = INST_TYPE [alpha |-> Type`:num`] EQ_SYM_EQ;
(*---------------------------------------------------------------------------*)
(* Definition of num_case more suitable to call-by-value computations *)
(*---------------------------------------------------------------------------*)
val num_case_compute = store_thm ("num_case_compute",
``!n. num_CASE n (f:'a) g = if n=0 then f else g (PRE n)``,
INDUCT_TAC THEN REWRITE_TAC [num_case_def,NOT_SUC,PRE]);
(* --------------------------------------------------------------------- *)
(* SUC_NOT = |- !n. ~(0 = SUC n) *)
(* --------------------------------------------------------------------- *)
val SUC_NOT = save_thm ("SUC_NOT",
GEN (``n:num``) (NOT_EQ_SYM (SPEC (``n:num``) NOT_SUC)));
val ADD_0 = store_thm ("ADD_0",
``!m. m + 0 = m``,
INDUCT_TAC THEN ASM_REWRITE_TAC[ADD]);
val ADD_SUC = store_thm ("ADD_SUC",
``!m n. SUC(m + n) = (m + SUC n)``,
INDUCT_TAC THEN ASM_REWRITE_TAC[ADD]);
val ADD_CLAUSES = store_thm ("ADD_CLAUSES",
``(0 + m = m) /\
(m + 0 = m) /\
(SUC m + n = SUC(m + n)) /\
(m + SUC n = SUC(m + n))``,
REWRITE_TAC[ADD, ADD_0, ADD_SUC]);
val ADD_SYM = store_thm ("ADD_SYM",
``!m n. m + n = n + m``,
INDUCT_TAC THEN ASM_REWRITE_TAC[ADD_0, ADD, ADD_SUC]);
val ADD_COMM = save_thm ("ADD_COMM", ADD_SYM);
val ADD_ASSOC = store_thm ("ADD_ASSOC",
``!m n p. m + (n + p) = (m + n) + p``,
INDUCT_TAC THEN ASM_REWRITE_TAC[ADD_CLAUSES]);
val num_CASES = store_thm ("num_CASES",
``!m. (m = 0) \/ ?n. m = SUC n``,
INDUCT_TAC
THEN REWRITE_TAC[NOT_SUC]
THEN EXISTS_TAC (``(m:num)``)
THEN REWRITE_TAC[]);
val NOT_ZERO_LT_ZERO = store_thm ("NOT_ZERO_LT_ZERO",
``!n. ~(n = 0) = 0 < n``,
GEN_TAC THEN STRUCT_CASES_TAC (Q.SPEC `n` num_CASES) THEN
REWRITE_TAC [NOT_LESS_0, LESS_0, NOT_SUC]);
val NOT_LT_ZERO_EQ_ZERO = store_thm(
"NOT_LT_ZERO_EQ_ZERO[simp]",
``!n. ~(0 < n) <=> (n = 0)``,
REWRITE_TAC [GSYM NOT_ZERO_LT_ZERO]);
val LESS_OR_EQ_ALT = store_thm ("LESS_OR_EQ_ALT",
``$<= = RTC (λx y. y = SUC x)``,
REWRITE_TAC [FUN_EQ_THM, LESS_OR_EQ, relationTheory.RTC_CASES_TC, LESS_ALT]
THEN REPEAT (STRIP_TAC ORELSE EQ_TAC)
THEN ASM_REWRITE_TAC []) ;
(* --------------------------------------------------------------------- *)
(* LESS_ADD proof rewritten: TFM 90.O9.21 *)
(* --------------------------------------------------------------------- *)
val LESS_ADD = store_thm ("LESS_ADD",
``!m n. n<m ==> ?p. p+n = m``,
INDUCT_TAC THEN GEN_TAC THEN
REWRITE_TAC[NOT_LESS_0,LESS_THM] THEN
REPEAT STRIP_TAC THENL
[EXISTS_TAC (``SUC 0``) THEN ASM_REWRITE_TAC[ADD],
RES_THEN (STRIP_THM_THEN (SUBST1_TAC o SYM)) THEN
EXISTS_TAC (``SUC p``) THEN REWRITE_TAC [ADD]]);
val transitive_LESS = store_thm(
"transitive_LESS[simp]",
``transitive $<``,
REWRITE_TAC [relationTheory.TC_TRANSITIVE, LESS_ALT]);
val LESS_TRANS = store_thm ("LESS_TRANS",
``!m n p. (m < n) /\ (n < p) ==> (m < p)``,
MATCH_ACCEPT_TAC
(REWRITE_RULE [relationTheory.transitive_def] transitive_LESS)) ;
val LESS_ANTISYM = store_thm ("LESS_ANTISYM",
``!m n. ~((m < n) /\ (n < m))``,
REPEAT STRIP_TAC
THEN IMP_RES_TAC LESS_TRANS
THEN IMP_RES_TAC LESS_REFL);
(*---------------------------------------------------------------------------
* |- !m n. SUC m < SUC n = m < n
*---------------------------------------------------------------------------*)
val LESS_MONO_REV = save_thm ("LESS_MONO_REV", prim_recTheory.LESS_MONO_REV) ;
val LESS_MONO_EQ = save_thm ("LESS_MONO_EQ", prim_recTheory.LESS_MONO_EQ) ;
val LESS_EQ_MONO = store_thm ("LESS_EQ_MONO",
``!n m. (SUC n <= SUC m) = (n <= m)``,
REWRITE_TAC [LESS_OR_EQ,LESS_MONO_EQ,INV_SUC_EQ]);
val LESS_LESS_SUC = store_thm ("LESS_LESS_SUC",
``!m n. ~((m < n) /\ (n < SUC m))``,
INDUCT_TAC THEN INDUCT_TAC THEN
ASM_REWRITE_TAC[LESS_MONO_EQ, LESS_EQ_MONO, LESS_0, NOT_LESS_0]) ;
val transitive_measure = Q.store_thm ("transitive_measure",
`!f. transitive (measure f)`,
SRW_TAC [][relationTheory.transitive_def,prim_recTheory.measure_thm]
THEN MATCH_MP_TAC LESS_TRANS
THEN SRW_TAC [SatisfySimps.SATISFY_ss][]);
val LESS_EQ = store_thm ("LESS_EQ",
``!m n. (m < n) = (SUC m <= n)``,
REWRITE_TAC[LESS_OR_EQ_ALT, LESS_ALT, RTC_IM_TC]) ;
val LESS_OR = store_thm ("LESS_OR",
``!m n. m < n ==> SUC m <= n``,
REWRITE_TAC[LESS_EQ]) ;
val LESS_SUC_EQ = LESS_OR;
val OR_LESS = store_thm ("OR_LESS",
``!m n. (SUC m <= n) ==> (m < n)``,
REWRITE_TAC[LESS_EQ]) ;
val LESS_EQ_IFF_LESS_SUC = store_thm ("LESS_EQ_IFF_LESS_SUC",
``!n m. (n <= m) = (n < (SUC m))``,
REWRITE_TAC[LESS_OR_EQ_ALT, LESS_ALT, TC_IM_RTC_SUC]) ;
val LESS_EQ_IMP_LESS_SUC = store_thm ("LESS_EQ_IMP_LESS_SUC",
``!n m. (n <= m) ==> (n < (SUC m))``,
REWRITE_TAC [LESS_EQ_IFF_LESS_SUC]) ;
val ZERO_LESS_EQ = store_thm ("ZERO_LESS_EQ",
``!n. 0 <= n``,
REWRITE_TAC [LESS_0,LESS_EQ_IFF_LESS_SUC]);
val LESS_SUC_EQ_COR = store_thm ("LESS_SUC_EQ_COR",
``!m n. ((m < n) /\ (~(SUC m = n))) ==> (SUC m < n)``,
CONV_TAC (ONCE_DEPTH_CONV SYM_CONV) THEN
INDUCT_TAC THEN INDUCT_TAC THEN
ASM_REWRITE_TAC [LESS_MONO_EQ, INV_SUC_EQ, LESS_0, NOT_LESS_0,
NOT_ZERO_LT_ZERO]) ;
val LESS_NOT_SUC = store_thm ("LESS_NOT_SUC",
``!m n. (m < n) /\ ~(n = SUC m) ==> SUC m < n``,
INDUCT_TAC THEN INDUCT_TAC THEN
ASM_REWRITE_TAC [LESS_MONO_EQ, INV_SUC_EQ, LESS_0, NOT_LESS_0,
NOT_ZERO_LT_ZERO]) ;
val LESS_0_CASES = store_thm ("LESS_0_CASES",
``!m. (0 = m) \/ 0<m``,
INDUCT_TAC
THEN REWRITE_TAC[LESS_0]);
val LESS_CASES_IMP = store_thm ("LESS_CASES_IMP",
``!m n. ~(m < n) /\ ~(m = n) ==> (n < m)``,
INDUCT_TAC THEN INDUCT_TAC THEN
ASM_REWRITE_TAC [LESS_MONO_EQ, INV_SUC_EQ, LESS_0, NOT_LESS_0]) ;
val LESS_CASES = store_thm ("LESS_CASES",
``!m n. (m < n) \/ (n <= m)``,
INDUCT_TAC THEN INDUCT_TAC THEN
ASM_REWRITE_TAC
[LESS_MONO_EQ, LESS_EQ_MONO, ZERO_LESS_EQ, LESS_0, NOT_LESS_0]) ;
val ADD_INV_0 = store_thm ("ADD_INV_0",
``!m n. (m + n = m) ==> (n = 0)``,
INDUCT_TAC THEN ASM_REWRITE_TAC[ADD_CLAUSES, INV_SUC_EQ]);
val LESS_EQ_ADD = store_thm ("LESS_EQ_ADD",
``!m n. m <= m + n``,
GEN_TAC
THEN REWRITE_TAC[LESS_OR_EQ]
THEN INDUCT_TAC
THEN ASM_REWRITE_TAC[ADD_CLAUSES]
THEN MP_TAC(ASSUME (``(m < (m + n)) \/ (m = (m + n))``))
THEN STRIP_TAC
THENL
[IMP_RES_TAC LESS_SUC
THEN ASM_REWRITE_TAC[],
REWRITE_TAC[SYM(ASSUME (``m = m + n``)),LESS_SUC_REFL]]);
val LESS_EQ_ADD_EXISTS = store_thm ("LESS_EQ_ADD_EXISTS",
``!m n. n<=m ==> ?p. p+n = m``,
SIMP_TAC bool_ss [LESS_OR_EQ, DISJ_IMP_THM, FORALL_AND_THM, LESS_ADD]
THEN GEN_TAC
THEN EXISTS_TAC (``0``)
THEN REWRITE_TAC[ADD]);
val LESS_STRONG_ADD = store_thm ("LESS_STRONG_ADD",
``!m n. n < m ==> ?p. (SUC p)+n = m``,
REPEAT STRIP_TAC
THEN IMP_RES_TAC LESS_OR
THEN IMP_RES_TAC LESS_EQ_ADD_EXISTS
THEN EXISTS_TAC (``p:num``)
THEN FULL_SIMP_TAC bool_ss [ADD_CLAUSES]);
val LESS_EQ_SUC_REFL = store_thm ("LESS_EQ_SUC_REFL",
``!m. m <= SUC m``,
GEN_TAC
THEN REWRITE_TAC[LESS_OR_EQ,LESS_SUC_REFL]);
val LESS_ADD_NONZERO = store_thm ("LESS_ADD_NONZERO",
``!m n. ~(n = 0) ==> m < m + n``,
GEN_TAC
THEN INDUCT_TAC
THEN REWRITE_TAC[NOT_SUC,ADD_CLAUSES]
THEN ASM_CASES_TAC (``n = 0``)
THEN ASSUME_TAC(SPEC (``m + n``) LESS_SUC_REFL)
THEN RES_TAC
THEN IMP_RES_TAC LESS_TRANS
THEN ASM_REWRITE_TAC[ADD_CLAUSES,LESS_SUC_REFL]);
val NOT_SUC_LESS_EQ_0 = store_thm ("NOT_SUC_LESS_EQ_0",
``!n. ~(SUC n <= 0)``,
REWRITE_TAC [NOT_LESS_0, GSYM LESS_EQ]);
val NOT_LESS = store_thm ("NOT_LESS",
``!m n. ~(m < n) = (n <= m)``,
INDUCT_TAC THEN INDUCT_TAC THEN
ASM_REWRITE_TAC [LESS_MONO_EQ, LESS_EQ_MONO,
ZERO_LESS_EQ, LESS_0, NOT_LESS_0, NOT_SUC_LESS_EQ_0]) ;
val NOT_LESS_EQUAL = store_thm ("NOT_LESS_EQUAL",
``!m n. ~(m <= n) = n < m``,
REWRITE_TAC[GSYM NOT_LESS]);
val LESS_EQ_ANTISYM = store_thm ("LESS_EQ_ANTISYM",
``!m n. ~(m < n /\ n <= m)``,
INDUCT_TAC THEN INDUCT_TAC THEN
ASM_REWRITE_TAC [LESS_MONO_EQ, LESS_EQ_MONO,
ZERO_LESS_EQ, LESS_0, NOT_LESS_0, NOT_SUC_LESS_EQ_0]) ;
val _ = print "Now proving properties of subtraction\n"
val SUB_0 = store_thm ("SUB_0",
``!m. (0 - m = 0) /\ (m - 0 = m)``,
INDUCT_TAC
THEN ASM_REWRITE_TAC[SUB, NOT_LESS_0]);
(* I was exhausted when I did the proof below - it can almostly certainly be
drastically shortened. *)
val SUB_EQ_0 = store_thm ("SUB_EQ_0",
``!m n. (m - n = 0) = (m <= n)``,
INDUCT_TAC
THEN GEN_TAC
THEN REWRITE_TAC[SUB,LESS_OR_EQ]
THENL
[REWRITE_TAC[SPECL[``0 < n``, ``0 = n``]DISJ_SYM,LESS_0_CASES],
ALL_TAC]
THEN ASM_CASES_TAC (``m < n``)
THEN ASM_CASES_TAC (``SUC m = n``)
THEN IMP_RES_TAC EQ_LESS
THEN IMP_RES_TAC LESS_SUC_EQ_COR
THEN IMP_RES_TAC(fst(EQ_IMP_RULE(SPEC_ALL NOT_LESS)))
THEN IMP_RES_TAC(fst(EQ_IMP_RULE(SPEC_ALL LESS_OR_EQ)))
THEN ASM_REWRITE_TAC
[SPECL[``(n:num)=m``,``n<m``]DISJ_SYM,
NOT_SUC,NOT_LESS,LESS_OR_EQ,LESS_THM]);
val ADD1 = store_thm ("ADD1",
``!m. SUC m = m + 1``,
INDUCT_TAC THENL [
REWRITE_TAC [ADD_CLAUSES, ONE],
ASM_REWRITE_TAC [] THEN REWRITE_TAC [ONE, ADD_CLAUSES]
]);
val SUC_SUB1 = store_thm ("SUC_SUB1",
``!m. SUC m - 1 = m``,
INDUCT_TAC THENL [
REWRITE_TAC [SUB, LESS_0, ONE],
PURE_ONCE_REWRITE_TAC[SUB] THEN
ASM_REWRITE_TAC[NOT_LESS_0, LESS_MONO_EQ, ONE]
]);
val PRE_SUB1 = store_thm ("PRE_SUB1",
``!m. (PRE m = (m - 1))``,
GEN_TAC
THEN STRUCT_CASES_TAC(SPEC (``m:num``) num_CASES)
THEN ASM_REWRITE_TAC[PRE, CONJUNCT1 SUB, SUC_SUB1]);
val MULT_0 = store_thm ("MULT_0",
``!m. m * 0 = 0``,
INDUCT_TAC
THEN ASM_REWRITE_TAC[MULT,ADD_CLAUSES]);
val MULT_SUC = store_thm ("MULT_SUC",
``!m n. m * (SUC n) = m + m*n``,
INDUCT_TAC
THEN ASM_REWRITE_TAC[MULT,ADD_CLAUSES,ADD_ASSOC]);
val MULT_LEFT_1 = store_thm ("MULT_LEFT_1",
``!m. 1 * m = m``,
GEN_TAC THEN REWRITE_TAC[ONE, MULT,ADD_CLAUSES]);
val MULT_RIGHT_1 = store_thm ("MULT_RIGHT_1",
``!m. m * 1 = m``,
REWRITE_TAC [ONE] THEN INDUCT_TAC THEN
ASM_REWRITE_TAC[MULT, ADD_CLAUSES]);
val MULT_CLAUSES = store_thm ("MULT_CLAUSES",
``!m n. (0 * m = 0) /\
(m * 0 = 0) /\
(1 * m = m) /\
(m * 1 = m) /\
(SUC m * n = m * n + n) /\
(m * SUC n = m + m * n)``,
REWRITE_TAC[MULT,MULT_0,MULT_LEFT_1,MULT_RIGHT_1,MULT_SUC]);
val MULT_SYM = store_thm ("MULT_SYM",
``!m n. m * n = n * m``,
INDUCT_TAC
THEN GEN_TAC
THEN ASM_REWRITE_TAC[MULT_CLAUSES,SPECL[``m*n``,``n:num``]ADD_SYM]);
val MULT_COMM = save_thm ("MULT_COMM", MULT_SYM);
val RIGHT_ADD_DISTRIB = store_thm ("RIGHT_ADD_DISTRIB",
``!m n p. (m + n) * p = (m * p) + (n * p)``,
GEN_TAC
THEN GEN_TAC
THEN INDUCT_TAC
THEN ASM_REWRITE_TAC[MULT_CLAUSES,ADD_CLAUSES,ADD_ASSOC]
THEN REWRITE_TAC[SPECL[``m+(m*p)``,``n:num``]ADD_SYM,ADD_ASSOC]
THEN SUBST_TAC[SPEC_ALL ADD_SYM]
THEN REWRITE_TAC[]);
(* A better proof of LEFT_ADD_DISTRIB would be using
MULT_SYM and RIGHT_ADD_DISTRIB *)
val LEFT_ADD_DISTRIB = store_thm ("LEFT_ADD_DISTRIB",
``!m n p. p * (m + n) = (p * m) + (p * n)``,
GEN_TAC
THEN GEN_TAC
THEN INDUCT_TAC
THEN ASM_REWRITE_TAC[MULT_CLAUSES,ADD_CLAUSES,SYM(SPEC_ALL ADD_ASSOC)]
THEN REWRITE_TAC[SPECL[``m:num``,``(p*n)+n``]ADD_SYM,
SYM(SPEC_ALL ADD_ASSOC)]
THEN SUBST_TAC[SPEC_ALL ADD_SYM]
THEN REWRITE_TAC[]);
val MULT_ASSOC = store_thm ("MULT_ASSOC",
``!m n p. m * (n * p) = (m * n) * p``,
INDUCT_TAC
THEN ASM_REWRITE_TAC[MULT_CLAUSES,RIGHT_ADD_DISTRIB]);
val SUB_ADD = store_thm ("SUB_ADD",
``!m n. (n <= m) ==> ((m - n) + n = m)``,
INDUCT_TAC
THEN REWRITE_TAC[LESS_OR_EQ]
THEN REPEAT STRIP_TAC
THEN ASM_REWRITE_TAC[SUB,ADD_CLAUSES,LESS_SUC_REFL]
THEN IMP_RES_TAC NOT_LESS_0
THEN ASM_CASES_TAC (``m < n``)
THEN IMP_RES_TAC LESS_LESS_SUC
THEN IMP_RES_TAC(fst(EQ_IMP_RULE(SPEC_ALL NOT_LESS)))
THEN RES_TAC
THEN ASM_REWRITE_TAC[ADD_CLAUSES]);
val PRE_SUB = store_thm ("PRE_SUB",
``!m n. PRE(m - n) = (PRE m) - n``,
INDUCT_TAC
THEN GEN_TAC
THEN ASM_REWRITE_TAC[SUB,PRE]
THEN ASM_CASES_TAC (``m < n``)
THEN ASM_REWRITE_TAC
[PRE,LESS_OR_EQ,
SUBS[SPECL[``m-n``,``0``]EQ_SYM_EQ']
(SPECL [``m:num``,``n:num``] SUB_EQ_0)])
val ADD_EQ_0 = store_thm ("ADD_EQ_0",
``!m n. (m + n = 0) = (m = 0) /\ (n = 0)``,
INDUCT_TAC
THEN GEN_TAC
THEN ASM_REWRITE_TAC[ADD_CLAUSES,NOT_SUC]);
val ADD_EQ_1 = store_thm ("ADD_EQ_1",
``!m n. (m + n = 1) = (m = 1) /\ (n = 0) \/ (m = 0) /\ (n = 1)``,
INDUCT_TAC THENL [
REWRITE_TAC [ADD_CLAUSES, ONE, GSYM NOT_SUC],
REWRITE_TAC [NOT_SUC, ADD_CLAUSES, ONE, INV_SUC_EQ, ADD_EQ_0]
]);
val ADD_INV_0_EQ = store_thm ("ADD_INV_0_EQ",
``!m n. (m + n = m) = (n = 0)``,
REPEAT GEN_TAC
THEN EQ_TAC
THEN REWRITE_TAC[ADD_INV_0]
THEN STRIP_TAC
THEN ASM_REWRITE_TAC[ADD_CLAUSES]);
val PRE_SUC_EQ = store_thm ("PRE_SUC_EQ",
``!m n. 0<n ==> ((m = PRE n) = (SUC m = n))``,
INDUCT_TAC
THEN INDUCT_TAC
THEN REWRITE_TAC[PRE,LESS_REFL,INV_SUC_EQ]);
val INV_PRE_EQ = store_thm ("INV_PRE_EQ",
``!m n. 0<m /\ 0<n ==> ((PRE m = (PRE n)) = (m = n))``,
INDUCT_TAC
THEN INDUCT_TAC
THEN REWRITE_TAC[PRE,LESS_REFL,INV_SUC_EQ]);
val LESS_SUC_NOT = store_thm ("LESS_SUC_NOT",
``!m n. (m < n) ==> ~(n < SUC m)``,
REPEAT GEN_TAC
THEN ASM_REWRITE_TAC[NOT_LESS]
THEN REPEAT STRIP_TAC
THEN IMP_RES_TAC LESS_OR
THEN ASM_REWRITE_TAC[]);
(* About now I burned out and resorted to dreadful hacks. The name of the
next theorem speaks for itself. *)
val TOTALLY_AD_HOC_LEMMA = prove(
``!m n. (m + SUC n = n) = (SUC m = 0)``,
REPEAT GEN_TAC
THEN REWRITE_TAC
[NOT_SUC,SYM(SPECL [``m:num``,``n:num``] (CONJUNCT2 ADD)),
(fn [_, _, _, th] => th | _ => raise Match) (CONJUNCTS ADD_CLAUSES)]
THEN REWRITE_TAC[SPECL[``SUC m``,``n:num``]ADD_SYM]
THEN STRIP_TAC
THEN IMP_RES_TAC ADD_INV_0
THEN IMP_RES_TAC NOT_SUC);
(* The next proof took me ages - there must be a better way! *)
val ADD_EQ_SUB = store_thm ("ADD_EQ_SUB",
``!m n p. (n <= p) ==> (((m + n) = p) = (m = (p - n)))``,
INDUCT_TAC
THEN INDUCT_TAC
THEN INDUCT_TAC
THEN ASM_REWRITE_TAC
[LESS_OR_EQ,ADD_CLAUSES,NOT_LESS_0,INV_SUC_EQ,LESS_MONO_EQ,
NOT_SUC,NOT_EQ_SYM(SPEC_ALL NOT_SUC),LESS_0,SUB,SUB_0]
THEN STRIP_TAC
THEN IMP_RES_TAC LESS_NOT_EQ
THEN ASM_REWRITE_TAC[LESS_SUC_REFL]
THEN IMP_RES_TAC LESS_SUC_NOT
THEN ASM_REWRITE_TAC[NOT_EQ_SYM(SPEC_ALL NOT_SUC),INV_SUC_EQ]
THEN IMP_RES_TAC(fst(EQ_IMP_RULE(SPEC_ALL NOT_LESS)))
THEN RES_TAC
THEN ASM_REWRITE_TAC
[SYM ((fn [_, _, _, th] => th | _ => raise Match)
(CONJUNCTS (SPEC_ALL ADD_CLAUSES))),
TOTALLY_AD_HOC_LEMMA]);
val LESS_MONO_ADD = store_thm ("LESS_MONO_ADD",
``!m n p. (m < n) ==> (m + p) < (n + p)``,
GEN_TAC
THEN GEN_TAC
THEN INDUCT_TAC
THEN DISCH_TAC
THEN RES_TAC
THEN ASM_REWRITE_TAC[ADD_CLAUSES,LESS_MONO_EQ]);
val LESS_MONO_ADD_INV = store_thm ("LESS_MONO_ADD_INV",
``!m n p. (m + p) < (n + p) ==> (m < n)``,
GEN_TAC
THEN GEN_TAC
THEN INDUCT_TAC
THEN ASM_REWRITE_TAC[ADD_CLAUSES,LESS_MONO_EQ]);
val LESS_MONO_ADD_EQ = store_thm ("LESS_MONO_ADD_EQ",
``!m n p. ((m + p) < (n + p)) = (m < n)``,
REPEAT GEN_TAC
THEN EQ_TAC
THEN REWRITE_TAC[LESS_MONO_ADD,LESS_MONO_ADD_INV]);
val LT_ADD_RCANCEL = save_thm ("LT_ADD_RCANCEL", LESS_MONO_ADD_EQ)
val LT_ADD_LCANCEL = save_thm ("LT_ADD_LCANCEL",
ONCE_REWRITE_RULE [ADD_COMM] LT_ADD_RCANCEL)
val EQ_MONO_ADD_EQ = store_thm ("EQ_MONO_ADD_EQ",
``!m n p. ((m + p) = (n + p)) = (m = n)``,
GEN_TAC
THEN GEN_TAC
THEN INDUCT_TAC
THEN ASM_REWRITE_TAC[ADD_CLAUSES,INV_SUC_EQ]);
val _ = print "Proving properties of <=\n"
val LESS_EQ_MONO_ADD_EQ = store_thm ("LESS_EQ_MONO_ADD_EQ",
``!m n p. ((m + p) <= (n + p)) = (m <= n)``,
REPEAT GEN_TAC
THEN REWRITE_TAC[LESS_OR_EQ]
THEN REPEAT STRIP_TAC
THEN REWRITE_TAC[LESS_MONO_ADD_EQ,EQ_MONO_ADD_EQ]);
val LESS_EQ_TRANS = store_thm ("LESS_EQ_TRANS",
``!m n p. (m <= n) /\ (n <= p) ==> (m <= p)``,
REWRITE_TAC[LESS_OR_EQ_ALT, REWRITE_RULE
[relationTheory.transitive_def] relationTheory.transitive_RTC]) ;
(* % Proof modified for new IMP_RES_TAC [TFM 90.04.25] *)
val LESS_EQ_LESS_EQ_MONO = store_thm ("LESS_EQ_LESS_EQ_MONO",
``!m n p q. (m <= p) /\ (n <= q) ==> ((m + n) <= (p + q))``,
REPEAT STRIP_TAC THEN
let val th1 = snd(EQ_IMP_RULE (SPEC_ALL LESS_EQ_MONO_ADD_EQ))
val th2 = PURE_ONCE_REWRITE_RULE [ADD_SYM] th1
in
IMP_RES_THEN (ASSUME_TAC o SPEC (``n:num``)) th1 THEN
IMP_RES_THEN (ASSUME_TAC o SPEC (``p:num``)) th2 THEN
IMP_RES_TAC LESS_EQ_TRANS
end);
val LESS_EQ_REFL = store_thm ("LESS_EQ_REFL",
``!m. m <= m``,
GEN_TAC
THEN REWRITE_TAC[LESS_OR_EQ]);
val LESS_IMP_LESS_OR_EQ = store_thm ("LESS_IMP_LESS_OR_EQ",
``!m n. (m < n) ==> (m <= n)``,
REPEAT STRIP_TAC
THEN ASM_REWRITE_TAC[LESS_OR_EQ]);
val LESS_MONO_MULT = store_thm ("LESS_MONO_MULT",
``!m n p. (m <= n) ==> ((m * p) <= (n * p))``,
GEN_TAC
THEN GEN_TAC
THEN INDUCT_TAC
THEN DISCH_TAC
THEN ASM_REWRITE_TAC
[ADD_CLAUSES,MULT_CLAUSES,LESS_EQ_MONO_ADD_EQ,LESS_EQ_REFL]
THEN RES_TAC
THEN IMP_RES_TAC(SPECL[``m:num``,``m*p``,``n:num``,``n*p``]
LESS_EQ_LESS_EQ_MONO)
THEN ASM_REWRITE_TAC[]);
val LESS_MONO_MULT2 = store_thm ("LESS_MONO_MULT2",
``!m n i j. m <= i /\ n <= j ==> m * n <= i * j``,
mesonLib.MESON_TAC [LESS_EQ_TRANS, LESS_MONO_MULT, MULT_COMM]);
(* Proof modified for new IMP_RES_TAC [TFM 90.04.25] *)
val RIGHT_SUB_DISTRIB = store_thm ("RIGHT_SUB_DISTRIB",
``!m n p. (m - n) * p = (m * p) - (n * p)``,
REPEAT GEN_TAC THEN
ASM_CASES_TAC (``n <= m``) THENL
[let val imp = SPECL [``(m-n)*p``,
``n*p``,
``m*p``] ADD_EQ_SUB
in
IMP_RES_THEN (SUBST1_TAC o SYM o MP imp o SPEC (``p:num``))
LESS_MONO_MULT THEN
REWRITE_TAC[SYM(SPEC_ALL RIGHT_ADD_DISTRIB)] THEN
IMP_RES_THEN SUBST1_TAC SUB_ADD THEN REFL_TAC
end,
IMP_RES_TAC (REWRITE_RULE[](AP_TERM (``$~``)
(SPEC_ALL NOT_LESS))) THEN
IMP_RES_TAC LESS_IMP_LESS_OR_EQ THEN
IMP_RES_THEN (ASSUME_TAC o SPEC (``p:num``)) LESS_MONO_MULT THEN
IMP_RES_TAC SUB_EQ_0 THEN
ASM_REWRITE_TAC[MULT_CLAUSES]]);
val LEFT_SUB_DISTRIB = store_thm ("LEFT_SUB_DISTRIB",
``!m n p. p * (m - n) = (p * m) - (p * n)``,
PURE_ONCE_REWRITE_TAC [MULT_SYM] THEN
REWRITE_TAC [RIGHT_SUB_DISTRIB]);
(* The following theorem (and proof) are from tfm [rewritten TFM 90.09.21] *)
val LESS_ADD_1 = store_thm ("LESS_ADD_1",
``!m n. (n<m) ==> ?p. m = n + (p + 1)``,
REWRITE_TAC [ONE] THEN INDUCT_TAC THEN
REWRITE_TAC[NOT_LESS_0,LESS_THM] THEN
REPEAT STRIP_TAC THENL [
EXISTS_TAC (``0``) THEN ASM_REWRITE_TAC [ADD_CLAUSES],
RES_THEN (STRIP_THM_THEN SUBST1_TAC) THEN
EXISTS_TAC (``SUC p``) THEN REWRITE_TAC [ADD_CLAUSES]
]);
(* ---------------------------------------------------------------------*)
(* The following arithmetic theorems were added by TFM in 88.03.31 *)
(* *)
(* These are needed to build the recursive type definition package *)
(* ---------------------------------------------------------------------*)
val EXP_ADD = store_thm ("EXP_ADD",
``!p q n. n EXP (p+q) = (n EXP p) * (n EXP q)``,
INDUCT_TAC THEN
ASM_REWRITE_TAC [EXP,ADD_CLAUSES,MULT_CLAUSES,MULT_ASSOC]);
val NOT_ODD_EQ_EVEN = store_thm ("NOT_ODD_EQ_EVEN",
``!n m. ~(SUC(n + n) = (m + m))``,
REPEAT (INDUCT_TAC THEN REWRITE_TAC [ADD_CLAUSES]) THENL
[MATCH_ACCEPT_TAC NOT_SUC,
REWRITE_TAC [INV_SUC_EQ,NOT_EQ_SYM (SPEC_ALL NOT_SUC)],
REWRITE_TAC [INV_SUC_EQ,NOT_SUC],
ASM_REWRITE_TAC [INV_SUC_EQ]]);
val MULT_SUC_EQ = store_thm ("MULT_SUC_EQ",
``!p m n. ((n * (SUC p)) = (m * (SUC p))) = (n = m)``,
REPEAT STRIP_TAC THEN
STRIP_ASSUME_TAC (REWRITE_RULE [LESS_OR_EQ] (SPEC_ALL LESS_CASES)) THEN
ASM_REWRITE_TAC [] THENL
[ ALL_TAC
,
ONCE_REWRITE_TAC [EQ_SYM_EQ'] THEN
POP_ASSUM MP_TAC THEN
(MAP_EVERY SPEC_TAC [(``m:num``,``m:num``),
(``n:num``,``n:num``)
]) THEN
MAP_EVERY X_GEN_TAC [``m:num``,``n:num``] THEN
DISCH_TAC
] THEN
IMP_RES_THEN (fn th => REWRITE_TAC [NOT_EQ_SYM th]) LESS_NOT_EQ THEN
POP_ASSUM (STRIP_THM_THEN SUBST1_TAC o MATCH_MP LESS_ADD_1) THEN
REWRITE_TAC [MULT_CLAUSES,SYM(SPEC_ALL ADD_ASSOC)] THEN
ONCE_REWRITE_TAC [ADD_SYM] THEN REWRITE_TAC [EQ_MONO_ADD_EQ] THEN
REWRITE_TAC [RIGHT_ADD_DISTRIB,MULT_CLAUSES] THEN
ONCE_REWRITE_TAC [SPEC (``p * q``) ADD_SYM] THEN
ONCE_REWRITE_TAC [EQ_SYM_EQ] THEN
REWRITE_TAC [ADD_ASSOC,REWRITE_RULE [ADD_CLAUSES]
(SPEC (``0``) EQ_MONO_ADD_EQ)] THEN
ONCE_REWRITE_TAC [EQ_SYM_EQ] THEN
REWRITE_TAC [ONE, ADD_CLAUSES,NOT_SUC]);
val MULT_EXP_MONO = store_thm ("MULT_EXP_MONO",
``!p q n m.((n * ((SUC q) EXP p)) = (m * ((SUC q) EXP p))) = (n = m)``,
INDUCT_TAC THENL
[REWRITE_TAC [EXP,MULT_CLAUSES,ADD_CLAUSES],
ASM_REWRITE_TAC [EXP,MULT_ASSOC,MULT_SUC_EQ]]);
val LESS_EQUAL_ANTISYM = store_thm ("LESS_EQUAL_ANTISYM",
``!n m. n <= m /\ m <= n ==> (n = m)``,
REWRITE_TAC [LESS_OR_EQ] THEN
REPEAT STRIP_TAC THENL
[IMP_RES_TAC LESS_ANTISYM,
ASM_REWRITE_TAC[]]);
val LESS_ADD_SUC = store_thm ("LESS_ADD_SUC",
``!m n. m < m + SUC n``,
INDUCT_TAC THENL
[REWRITE_TAC [LESS_0,ADD_CLAUSES],
POP_ASSUM (ASSUME_TAC o REWRITE_RULE [ADD_CLAUSES]) THEN
ASM_REWRITE_TAC [LESS_MONO_EQ,ADD_CLAUSES]]);
(* Following proof revised for version 1.12 resolution. [TFM 91.01.18] *)
val LESS_OR_EQ_ADD = store_thm ("LESS_OR_EQ_ADD",
``!n m. n < m \/ ?p. n = p+m``,
REPEAT GEN_TAC THEN ASM_CASES_TAC (``n<m``) THENL
[DISJ1_TAC THEN FIRST_ASSUM ACCEPT_TAC,
DISJ2_TAC THEN IMP_RES_TAC NOT_LESS THEN IMP_RES_TAC LESS_OR_EQ THENL
[CONV_TAC (ONCE_DEPTH_CONV SYM_CONV) THEN
IMP_RES_THEN MATCH_ACCEPT_TAC LESS_ADD,
EXISTS_TAC (``0``) THEN ASM_REWRITE_TAC [ADD]]]);
(*----------------------------------------------------------------------*)
(* Added TFM 88.03.31 *)
(* *)
(* Prove the well ordering property: *)
(* *)
(* |- !P. (?n. P n) ==> (?n. P n /\ (!m. m < n ==> ~P m)) *)
(* *)
(* I.e. considering P to be a set, that is the set of numbers, x , such *)
(* that P(x), then every non-empty P has a smallest element. *)
(* *)
(* We first prove that, if there does NOT exist a smallest n such that *)
(* P(n) is true, then for all n P is false of all numbers smaller than n.*)
(* The main step is an induction on n. *)
(*----------------------------------------------------------------------*)
val lemma = TAC_PROOF(([],
``(~?n. P n /\ !m. (m<n) ==> ~P m) ==> (!n m. (m<n) ==> ~P m)``),
CONV_TAC (DEPTH_CONV NOT_EXISTS_CONV) THEN
DISCH_TAC THEN
INDUCT_TAC THEN
REWRITE_TAC [NOT_LESS_0,LESS_THM] THEN
REPEAT (FILTER_STRIP_TAC (``P:num->bool``)) THENL
[POP_ASSUM SUBST1_TAC THEN DISCH_TAC,ALL_TAC] THEN
RES_TAC);
(* We now prove the well ordering property. *)
val WOP = store_thm ("WOP",
``!P. (?n.P n) ==> (?n. P n /\ (!m. (m<n) ==> ~P m))``,
GEN_TAC THEN
CONV_TAC CONTRAPOS_CONV THEN
DISCH_THEN (ASSUME_TAC o MP lemma) THEN
CONV_TAC NOT_EXISTS_CONV THEN
GEN_TAC THEN
POP_ASSUM (MATCH_MP_TAC o SPECL [``SUC n``,``n:num``]) THEN
MATCH_ACCEPT_TAC LESS_SUC_REFL);
val COMPLETE_INDUCTION = store_thm ("COMPLETE_INDUCTION",
``!P. (!n. (!m. m < n ==> P m) ==> P n) ==> !n. P n``,
let val wopeta = CONV_RULE(ONCE_DEPTH_CONV ETA_CONV) WOP
in
GEN_TAC THEN CONV_TAC CONTRAPOS_CONV THEN
CONV_TAC(ONCE_DEPTH_CONV NOT_FORALL_CONV) THEN
DISCH_THEN(MP_TAC o MATCH_MP wopeta) THEN BETA_TAC THEN
REWRITE_TAC[NOT_IMP] THEN DISCH_THEN(X_CHOOSE_TAC (``n:num``)) THEN
EXISTS_TAC (``n:num``) THEN ASM_REWRITE_TAC[]
end);
val FORALL_NUM_THM = Q.store_thm ("FORALL_NUM_THM",
`(!n. P n) = P 0 /\ !n. P n ==> P (SUC n)`,
METIS_TAC [INDUCTION]);
(* ---------------------------------------------------------------------*)
(* Some more theorems, mostly about subtraction. *)
(* ---------------------------------------------------------------------*)
(* Non-confluence problem between SUB (snd clause) and LESS_MONO_EQ *)
(* requires a change from hol2 proof. kls. *)
val SUB_MONO_EQ = store_thm ("SUB_MONO_EQ",
``!n m. (SUC n) - (SUC m) = (n - m)``,
INDUCT_TAC THENL
[REWRITE_TAC [SUB,LESS_0],
ONCE_REWRITE_TAC[SUB] THEN
PURE_ONCE_REWRITE_TAC[LESS_MONO_EQ] THEN
ASM_REWRITE_TAC[]]);
val SUC_SUB = store_thm(
"SUC_SUB[simp]",
``!a. SUC a - a = 1``,
INDUCT_TAC THENL [
REWRITE_TAC [SUB, LESS_REFL, ONE],
ASM_REWRITE_TAC [SUB_MONO_EQ]
]);
val SUB_PLUS = store_thm ("SUB_PLUS",
``!a b c. a - (b + c) = (a - b) - c``,
REPEAT INDUCT_TAC THEN
REWRITE_TAC [SUB_0,ADD_CLAUSES,SUB_MONO_EQ] THEN
PURE_ONCE_REWRITE_TAC [SYM (el 4 (CONJUNCTS ADD_CLAUSES))] THEN
PURE_ONCE_ASM_REWRITE_TAC [] THEN REFL_TAC);
(* Statement of thm changed.
**val INV_PRE_LESS = store_thm ("INV_PRE_LESS",
** ``!m n. 0 < m /\ 0 < n ==> ((PRE m < PRE n) = (m < n))``,
** REPEAT INDUCT_TAC THEN
** REWRITE_TAC[LESS_REFL,SUB,LESS_0,PRE] THEN
** MATCH_ACCEPT_TAC (SYM(SPEC_ALL LESS_MONO_EQ)));
*)
val INV_PRE_LESS = store_thm ("INV_PRE_LESS",
``!m. 0 < m ==> !n. PRE m < PRE n = m < n``,
REPEAT (INDUCT_TAC THEN TRY DISCH_TAC) THEN
REWRITE_TAC[LESS_REFL,SUB,LESS_0,PRE,NOT_LESS_0] THEN
IMP_RES_TAC LESS_REFL THEN
MATCH_ACCEPT_TAC (SYM(SPEC_ALL LESS_MONO_EQ)));
val INV_PRE_LESS_EQ = store_thm ("INV_PRE_LESS_EQ",