(* Title: ZF/CardinalArith.thy
Author: Lawrence C Paulson, Cambridge University Computer Laboratory
Copyright 1994 University of Cambridge
*)
header{*Cardinal Arithmetic Without the Axiom of Choice*}
theory CardinalArith imports Cardinal OrderArith ArithSimp Finite begin
definition
InfCard :: "i=>o" where
"InfCard(i) == Card(i) & nat le i"
definition
cmult :: "[i,i]=>i" (infixl "|*|" 70) where
"i |*| j == |i*j|"
definition
cadd :: "[i,i]=>i" (infixl "|+|" 65) where
"i |+| j == |i+j|"
definition
csquare_rel :: "i=>i" where
"csquare_rel(K) ==
rvimage(K*K,
lam <x,y>:K*K. <x Un y, x, y>,
rmult(K,Memrel(K), K*K, rmult(K,Memrel(K), K,Memrel(K))))"
definition
jump_cardinal :: "i=>i" where
--{*This def is more complex than Kunen's but it more easily proved to
be a cardinal*}
"jump_cardinal(K) ==
\<Union>X\<in>Pow(K). {z. r: Pow(K*K), well_ord(X,r) & z = ordertype(X,r)}"
definition
csucc :: "i=>i" where
--{*needed because @{term "jump_cardinal(K)"} might not be the successor
of @{term K}*}
"csucc(K) == LEAST L. Card(L) & K<L"
notation (xsymbols output)
cadd (infixl "\<oplus>" 65) and
cmult (infixl "\<otimes>" 70)
notation (HTML output)
cadd (infixl "\<oplus>" 65) and
cmult (infixl "\<otimes>" 70)
lemma Card_Union [simp,intro,TC]: "(ALL x:A. Card(x)) ==> Card(Union(A))"
apply (rule CardI)
apply (simp add: Card_is_Ord)
apply (clarify dest!: ltD)
apply (drule bspec, assumption)
apply (frule lt_Card_imp_lesspoll, blast intro: ltI Card_is_Ord)
apply (drule eqpoll_sym [THEN eqpoll_imp_lepoll])
apply (drule lesspoll_trans1, assumption)
apply (subgoal_tac "B \<lesssim> \<Union>A")
apply (drule lesspoll_trans1, assumption, blast)
apply (blast intro: subset_imp_lepoll)
done
lemma Card_UN: "(!!x. x:A ==> Card(K(x))) ==> Card(\<Union>x\<in>A. K(x))"
by (blast intro: Card_Union)
lemma Card_OUN [simp,intro,TC]:
"(!!x. x:A ==> Card(K(x))) ==> Card(\<Union>x<A. K(x))"
by (simp add: OUnion_def Card_0)
lemma n_lesspoll_nat: "n \<in> nat ==> n \<prec> nat"
apply (unfold lesspoll_def)
apply (rule conjI)
apply (erule OrdmemD [THEN subset_imp_lepoll], rule Ord_nat)
apply (rule notI)
apply (erule eqpollE)
apply (rule succ_lepoll_natE)
apply (blast intro: nat_succI [THEN OrdmemD, THEN subset_imp_lepoll]
lepoll_trans, assumption)
done
lemma in_Card_imp_lesspoll: "[| Card(K); b \<in> K |] ==> b \<prec> K"
apply (unfold lesspoll_def)
apply (simp add: Card_iff_initial)
apply (fast intro!: le_imp_lepoll ltI leI)
done
lemma lesspoll_lemma: "[| ~ A \<prec> B; C \<prec> B |] ==> A - C \<noteq> 0"
apply (unfold lesspoll_def)
apply (fast dest!: Diff_eq_0_iff [THEN iffD1, THEN subset_imp_lepoll]
intro!: eqpollI elim: notE
elim!: eqpollE lepoll_trans)
done
subsection{*Cardinal addition*}
text{*Note: Could omit proving the algebraic laws for cardinal addition and
multiplication. On finite cardinals these operations coincide with
addition and multiplication of natural numbers; on infinite cardinals they
coincide with union (maximum). Either way we get most laws for free.*}
subsubsection{*Cardinal addition is commutative*}
lemma sum_commute_eqpoll: "A+B \<approx> B+A"
apply (unfold eqpoll_def)
apply (rule exI)
apply (rule_tac c = "case(Inr,Inl)" and d = "case(Inr,Inl)" in lam_bijective)
apply auto
done
lemma cadd_commute: "i |+| j = j |+| i"
apply (unfold cadd_def)
apply (rule sum_commute_eqpoll [THEN cardinal_cong])
done
subsubsection{*Cardinal addition is associative*}
lemma sum_assoc_eqpoll: "(A+B)+C \<approx> A+(B+C)"
apply (unfold eqpoll_def)
apply (rule exI)
apply (rule sum_assoc_bij)
done
(*Unconditional version requires AC*)
lemma well_ord_cadd_assoc:
"[| well_ord(i,ri); well_ord(j,rj); well_ord(k,rk) |]
==> (i |+| j) |+| k = i |+| (j |+| k)"
apply (unfold cadd_def)
apply (rule cardinal_cong)
apply (rule eqpoll_trans)
apply (rule sum_eqpoll_cong [OF well_ord_cardinal_eqpoll eqpoll_refl])
apply (blast intro: well_ord_radd )
apply (rule sum_assoc_eqpoll [THEN eqpoll_trans])
apply (rule eqpoll_sym)
apply (rule sum_eqpoll_cong [OF eqpoll_refl well_ord_cardinal_eqpoll])
apply (blast intro: well_ord_radd )
done
subsubsection{*0 is the identity for addition*}
lemma sum_0_eqpoll: "0+A \<approx> A"
apply (unfold eqpoll_def)
apply (rule exI)
apply (rule bij_0_sum)
done
lemma cadd_0 [simp]: "Card(K) ==> 0 |+| K = K"
apply (unfold cadd_def)
apply (simp add: sum_0_eqpoll [THEN cardinal_cong] Card_cardinal_eq)
done
subsubsection{*Addition by another cardinal*}
lemma sum_lepoll_self: "A \<lesssim> A+B"
apply (unfold lepoll_def inj_def)
apply (rule_tac x = "lam x:A. Inl (x) " in exI)
apply simp
done
(*Could probably weaken the premises to well_ord(K,r), or removing using AC*)
lemma cadd_le_self:
"[| Card(K); Ord(L) |] ==> K le (K |+| L)"
apply (unfold cadd_def)
apply (rule le_trans [OF Card_cardinal_le well_ord_lepoll_imp_Card_le],
assumption)
apply (rule_tac [2] sum_lepoll_self)
apply (blast intro: well_ord_radd well_ord_Memrel Card_is_Ord)
done
subsubsection{*Monotonicity of addition*}
lemma sum_lepoll_mono:
"[| A \<lesssim> C; B \<lesssim> D |] ==> A + B \<lesssim> C + D"
apply (unfold lepoll_def)
apply (elim exE)
apply (rule_tac x = "lam z:A+B. case (%w. Inl(f`w), %y. Inr(fa`y), z)" in exI)
apply (rule_tac d = "case (%w. Inl(converse(f) `w), %y. Inr(converse(fa) ` y))"
in lam_injective)
apply (typecheck add: inj_is_fun, auto)
done
lemma cadd_le_mono:
"[| K' le K; L' le L |] ==> (K' |+| L') le (K |+| L)"
apply (unfold cadd_def)
apply (safe dest!: le_subset_iff [THEN iffD1])
apply (rule well_ord_lepoll_imp_Card_le)
apply (blast intro: well_ord_radd well_ord_Memrel)
apply (blast intro: sum_lepoll_mono subset_imp_lepoll)
done
subsubsection{*Addition of finite cardinals is "ordinary" addition*}
lemma sum_succ_eqpoll: "succ(A)+B \<approx> succ(A+B)"
apply (unfold eqpoll_def)
apply (rule exI)
apply (rule_tac c = "%z. if z=Inl (A) then A+B else z"
and d = "%z. if z=A+B then Inl (A) else z" in lam_bijective)
apply simp_all
apply (blast dest: sym [THEN eq_imp_not_mem] elim: mem_irrefl)+
done
(*Pulling the succ(...) outside the |...| requires m, n: nat *)
(*Unconditional version requires AC*)
lemma cadd_succ_lemma:
"[| Ord(m); Ord(n) |] ==> succ(m) |+| n = |succ(m |+| n)|"
apply (unfold cadd_def)
apply (rule sum_succ_eqpoll [THEN cardinal_cong, THEN trans])
apply (rule succ_eqpoll_cong [THEN cardinal_cong])
apply (rule well_ord_cardinal_eqpoll [THEN eqpoll_sym])
apply (blast intro: well_ord_radd well_ord_Memrel)
done
lemma nat_cadd_eq_add: "[| m: nat; n: nat |] ==> m |+| n = m#+n"
apply (induct_tac m)
apply (simp add: nat_into_Card [THEN cadd_0])
apply (simp add: cadd_succ_lemma nat_into_Card [THEN Card_cardinal_eq])
done
subsection{*Cardinal multiplication*}
subsubsection{*Cardinal multiplication is commutative*}
(*Easier to prove the two directions separately*)
lemma prod_commute_eqpoll: "A*B \<approx> B*A"
apply (unfold eqpoll_def)
apply (rule exI)
apply (rule_tac c = "%<x,y>.<y,x>" and d = "%<x,y>.<y,x>" in lam_bijective,
auto)
done
lemma cmult_commute: "i |*| j = j |*| i"
apply (unfold cmult_def)
apply (rule prod_commute_eqpoll [THEN cardinal_cong])
done
subsubsection{*Cardinal multiplication is associative*}
lemma prod_assoc_eqpoll: "(A*B)*C \<approx> A*(B*C)"
apply (unfold eqpoll_def)
apply (rule exI)
apply (rule prod_assoc_bij)
done
(*Unconditional version requires AC*)
lemma well_ord_cmult_assoc:
"[| well_ord(i,ri); well_ord(j,rj); well_ord(k,rk) |]
==> (i |*| j) |*| k = i |*| (j |*| k)"
apply (unfold cmult_def)
apply (rule cardinal_cong)
apply (rule eqpoll_trans)
apply (rule prod_eqpoll_cong [OF well_ord_cardinal_eqpoll eqpoll_refl])
apply (blast intro: well_ord_rmult)
apply (rule prod_assoc_eqpoll [THEN eqpoll_trans])
apply (rule eqpoll_sym)
apply (rule prod_eqpoll_cong [OF eqpoll_refl well_ord_cardinal_eqpoll])
apply (blast intro: well_ord_rmult)
done
subsubsection{*Cardinal multiplication distributes over addition*}
lemma sum_prod_distrib_eqpoll: "(A+B)*C \<approx> (A*C)+(B*C)"
apply (unfold eqpoll_def)
apply (rule exI)
apply (rule sum_prod_distrib_bij)
done
lemma well_ord_cadd_cmult_distrib:
"[| well_ord(i,ri); well_ord(j,rj); well_ord(k,rk) |]
==> (i |+| j) |*| k = (i |*| k) |+| (j |*| k)"
apply (unfold cadd_def cmult_def)
apply (rule cardinal_cong)
apply (rule eqpoll_trans)
apply (rule prod_eqpoll_cong [OF well_ord_cardinal_eqpoll eqpoll_refl])
apply (blast intro: well_ord_radd)
apply (rule sum_prod_distrib_eqpoll [THEN eqpoll_trans])
apply (rule eqpoll_sym)
apply (rule sum_eqpoll_cong [OF well_ord_cardinal_eqpoll
well_ord_cardinal_eqpoll])
apply (blast intro: well_ord_rmult)+
done
subsubsection{*Multiplication by 0 yields 0*}
lemma prod_0_eqpoll: "0*A \<approx> 0"
apply (unfold eqpoll_def)
apply (rule exI)
apply (rule lam_bijective, safe)
done
lemma cmult_0 [simp]: "0 |*| i = 0"
by (simp add: cmult_def prod_0_eqpoll [THEN cardinal_cong])
subsubsection{*1 is the identity for multiplication*}
lemma prod_singleton_eqpoll: "{x}*A \<approx> A"
apply (unfold eqpoll_def)
apply (rule exI)
apply (rule singleton_prod_bij [THEN bij_converse_bij])
done
lemma cmult_1 [simp]: "Card(K) ==> 1 |*| K = K"
apply (unfold cmult_def succ_def)
apply (simp add: prod_singleton_eqpoll [THEN cardinal_cong] Card_cardinal_eq)
done
subsection{*Some inequalities for multiplication*}
lemma prod_square_lepoll: "A \<lesssim> A*A"
apply (unfold lepoll_def inj_def)
apply (rule_tac x = "lam x:A. <x,x>" in exI, simp)
done
(*Could probably weaken the premise to well_ord(K,r), or remove using AC*)
lemma cmult_square_le: "Card(K) ==> K le K |*| K"
apply (unfold cmult_def)
apply (rule le_trans)
apply (rule_tac [2] well_ord_lepoll_imp_Card_le)
apply (rule_tac [3] prod_square_lepoll)
apply (simp add: le_refl Card_is_Ord Card_cardinal_eq)
apply (blast intro: well_ord_rmult well_ord_Memrel Card_is_Ord)
done
subsubsection{*Multiplication by a non-zero cardinal*}
lemma prod_lepoll_self: "b: B ==> A \<lesssim> A*B"
apply (unfold lepoll_def inj_def)
apply (rule_tac x = "lam x:A. <x,b>" in exI, simp)
done
(*Could probably weaken the premises to well_ord(K,r), or removing using AC*)
lemma cmult_le_self:
"[| Card(K); Ord(L); 0<L |] ==> K le (K |*| L)"
apply (unfold cmult_def)
apply (rule le_trans [OF Card_cardinal_le well_ord_lepoll_imp_Card_le])
apply assumption
apply (blast intro: well_ord_rmult well_ord_Memrel Card_is_Ord)
apply (blast intro: prod_lepoll_self ltD)
done
subsubsection{*Monotonicity of multiplication*}
lemma prod_lepoll_mono:
"[| A \<lesssim> C; B \<lesssim> D |] ==> A * B \<lesssim> C * D"
apply (unfold lepoll_def)
apply (elim exE)
apply (rule_tac x = "lam <w,y>:A*B. <f`w, fa`y>" in exI)
apply (rule_tac d = "%<w,y>. <converse (f) `w, converse (fa) `y>"
in lam_injective)
apply (typecheck add: inj_is_fun, auto)
done
lemma cmult_le_mono:
"[| K' le K; L' le L |] ==> (K' |*| L') le (K |*| L)"
apply (unfold cmult_def)
apply (safe dest!: le_subset_iff [THEN iffD1])
apply (rule well_ord_lepoll_imp_Card_le)
apply (blast intro: well_ord_rmult well_ord_Memrel)
apply (blast intro: prod_lepoll_mono subset_imp_lepoll)
done
subsection{*Multiplication of finite cardinals is "ordinary" multiplication*}
lemma prod_succ_eqpoll: "succ(A)*B \<approx> B + A*B"
apply (unfold eqpoll_def)
apply (rule exI)
apply (rule_tac c = "%<x,y>. if x=A then Inl (y) else Inr (<x,y>)"
and d = "case (%y. <A,y>, %z. z)" in lam_bijective)
apply safe
apply (simp_all add: succI2 if_type mem_imp_not_eq)
done
(*Unconditional version requires AC*)
lemma cmult_succ_lemma:
"[| Ord(m); Ord(n) |] ==> succ(m) |*| n = n |+| (m |*| n)"
apply (unfold cmult_def cadd_def)
apply (rule prod_succ_eqpoll [THEN cardinal_cong, THEN trans])
apply (rule cardinal_cong [symmetric])
apply (rule sum_eqpoll_cong [OF eqpoll_refl well_ord_cardinal_eqpoll])
apply (blast intro: well_ord_rmult well_ord_Memrel)
done
lemma nat_cmult_eq_mult: "[| m: nat; n: nat |] ==> m |*| n = m#*n"
apply (induct_tac m)
apply (simp_all add: cmult_succ_lemma nat_cadd_eq_add)
done
lemma cmult_2: "Card(n) ==> 2 |*| n = n |+| n"
by (simp add: cmult_succ_lemma Card_is_Ord cadd_commute [of _ 0])
lemma sum_lepoll_prod: "2 \<lesssim> C ==> B+B \<lesssim> C*B"
apply (rule lepoll_trans)
apply (rule sum_eq_2_times [THEN equalityD1, THEN subset_imp_lepoll])
apply (erule prod_lepoll_mono)
apply (rule lepoll_refl)
done
lemma lepoll_imp_sum_lepoll_prod: "[| A \<lesssim> B; 2 \<lesssim> A |] ==> A+B \<lesssim> A*B"
by (blast intro: sum_lepoll_mono sum_lepoll_prod lepoll_trans lepoll_refl)
subsection{*Infinite Cardinals are Limit Ordinals*}
(*This proof is modelled upon one assuming nat<=A, with injection
lam z:cons(u,A). if z=u then 0 else if z : nat then succ(z) else z
and inverse %y. if y:nat then nat_case(u, %z. z, y) else y. \
If f: inj(nat,A) then range(f) behaves like the natural numbers.*)
lemma nat_cons_lepoll: "nat \<lesssim> A ==> cons(u,A) \<lesssim> A"
apply (unfold lepoll_def)
apply (erule exE)
apply (rule_tac x =
"lam z:cons (u,A).
if z=u then f`0
else if z: range (f) then f`succ (converse (f) `z) else z"
in exI)
apply (rule_tac d =
"%y. if y: range(f) then nat_case (u, %z. f`z, converse(f) `y)
else y"
in lam_injective)
apply (fast intro!: if_type apply_type intro: inj_is_fun inj_converse_fun)
apply (simp add: inj_is_fun [THEN apply_rangeI]
inj_converse_fun [THEN apply_rangeI]
inj_converse_fun [THEN apply_funtype])
done
lemma nat_cons_eqpoll: "nat \<lesssim> A ==> cons(u,A) \<approx> A"
apply (erule nat_cons_lepoll [THEN eqpollI])
apply (rule subset_consI [THEN subset_imp_lepoll])
done
(*Specialized version required below*)
lemma nat_succ_eqpoll: "nat <= A ==> succ(A) \<approx> A"
apply (unfold succ_def)
apply (erule subset_imp_lepoll [THEN nat_cons_eqpoll])
done
lemma InfCard_nat: "InfCard(nat)"
apply (unfold InfCard_def)
apply (blast intro: Card_nat le_refl Card_is_Ord)
done
lemma InfCard_is_Card: "InfCard(K) ==> Card(K)"
apply (unfold InfCard_def)
apply (erule conjunct1)
done
lemma InfCard_Un:
"[| InfCard(K); Card(L) |] ==> InfCard(K Un L)"
apply (unfold InfCard_def)
apply (simp add: Card_Un Un_upper1_le [THEN [2] le_trans] Card_is_Ord)
done
(*Kunen's Lemma 10.11*)
lemma InfCard_is_Limit: "InfCard(K) ==> Limit(K)"
apply (unfold InfCard_def)
apply (erule conjE)
apply (frule Card_is_Ord)
apply (rule ltI [THEN non_succ_LimitI])
apply (erule le_imp_subset [THEN subsetD])
apply (safe dest!: Limit_nat [THEN Limit_le_succD])
apply (unfold Card_def)
apply (drule trans)
apply (erule le_imp_subset [THEN nat_succ_eqpoll, THEN cardinal_cong])
apply (erule Ord_cardinal_le [THEN lt_trans2, THEN lt_irrefl])
apply (rule le_eqI, assumption)
apply (rule Ord_cardinal)
done
(*** An infinite cardinal equals its square (Kunen, Thm 10.12, page 29) ***)
(*A general fact about ordermap*)
lemma ordermap_eqpoll_pred:
"[| well_ord(A,r); x:A |] ==> ordermap(A,r)`x \<approx> Order.pred(A,x,r)"
apply (unfold eqpoll_def)
apply (rule exI)
apply (simp add: ordermap_eq_image well_ord_is_wf)
apply (erule ordermap_bij [THEN bij_is_inj, THEN restrict_bij,
THEN bij_converse_bij])
apply (rule pred_subset)
done
subsubsection{*Establishing the well-ordering*}
lemma csquare_lam_inj:
"Ord(K) ==> (lam <x,y>:K*K. <x Un y, x, y>) : inj(K*K, K*K*K)"
apply (unfold inj_def)
apply (force intro: lam_type Un_least_lt [THEN ltD] ltI)
done
lemma well_ord_csquare: "Ord(K) ==> well_ord(K*K, csquare_rel(K))"
apply (unfold csquare_rel_def)
apply (rule csquare_lam_inj [THEN well_ord_rvimage], assumption)
apply (blast intro: well_ord_rmult well_ord_Memrel)
done
subsubsection{*Characterising initial segments of the well-ordering*}
lemma csquareD:
"[| <<x,y>, <z,z>> : csquare_rel(K); x<K; y<K; z<K |] ==> x le z & y le z"
apply (unfold csquare_rel_def)
apply (erule rev_mp)
apply (elim ltE)
apply (simp add: rvimage_iff Un_absorb Un_least_mem_iff ltD)
apply (safe elim!: mem_irrefl intro!: Un_upper1_le Un_upper2_le)
apply (simp_all add: lt_def succI2)
done
lemma pred_csquare_subset:
"z<K ==> Order.pred(K*K, <z,z>, csquare_rel(K)) <= succ(z)*succ(z)"
apply (unfold Order.pred_def)
apply (safe del: SigmaI succCI)
apply (erule csquareD [THEN conjE])
apply (unfold lt_def, auto)
done
lemma csquare_ltI:
"[| x<z; y<z; z<K |] ==> <<x,y>, <z,z>> : csquare_rel(K)"
apply (unfold csquare_rel_def)
apply (subgoal_tac "x<K & y<K")
prefer 2 apply (blast intro: lt_trans)
apply (elim ltE)
apply (simp add: rvimage_iff Un_absorb Un_least_mem_iff ltD)
done
(*Part of the traditional proof. UNUSED since it's harder to prove & apply *)
lemma csquare_or_eqI:
"[| x le z; y le z; z<K |] ==> <<x,y>, <z,z>> : csquare_rel(K) | x=z & y=z"
apply (unfold csquare_rel_def)
apply (subgoal_tac "x<K & y<K")
prefer 2 apply (blast intro: lt_trans1)
apply (elim ltE)
apply (simp add: rvimage_iff Un_absorb Un_least_mem_iff ltD)
apply (elim succE)
apply (simp_all add: subset_Un_iff [THEN iff_sym]
subset_Un_iff2 [THEN iff_sym] OrdmemD)
done
subsubsection{*The cardinality of initial segments*}
lemma ordermap_z_lt:
"[| Limit(K); x<K; y<K; z=succ(x Un y) |] ==>
ordermap(K*K, csquare_rel(K)) ` <x,y> <
ordermap(K*K, csquare_rel(K)) ` <z,z>"
apply (subgoal_tac "z<K & well_ord (K*K, csquare_rel (K))")
prefer 2 apply (blast intro!: Un_least_lt Limit_has_succ
Limit_is_Ord [THEN well_ord_csquare], clarify)
apply (rule csquare_ltI [THEN ordermap_mono, THEN ltI])
apply (erule_tac [4] well_ord_is_wf)
apply (blast intro!: Un_upper1_le Un_upper2_le Ord_ordermap elim!: ltE)+
done
(*Kunen: "each <x,y>: K*K has no more than z*z predecessors..." (page 29) *)
lemma ordermap_csquare_le:
"[| Limit(K); x<K; y<K; z=succ(x Un y) |]
==> | ordermap(K*K, csquare_rel(K)) ` <x,y> | le |succ(z)| |*| |succ(z)|"
apply (unfold cmult_def)
apply (rule well_ord_rmult [THEN well_ord_lepoll_imp_Card_le])
apply (rule Ord_cardinal [THEN well_ord_Memrel])+
apply (subgoal_tac "z<K")
prefer 2 apply (blast intro!: Un_least_lt Limit_has_succ)
apply (rule ordermap_z_lt [THEN leI, THEN le_imp_lepoll, THEN lepoll_trans],
assumption+)
apply (rule ordermap_eqpoll_pred [THEN eqpoll_imp_lepoll, THEN lepoll_trans])
apply (erule Limit_is_Ord [THEN well_ord_csquare])
apply (blast intro: ltD)
apply (rule pred_csquare_subset [THEN subset_imp_lepoll, THEN lepoll_trans],
assumption)
apply (elim ltE)
apply (rule prod_eqpoll_cong [THEN eqpoll_sym, THEN eqpoll_imp_lepoll])
apply (erule Ord_succ [THEN Ord_cardinal_eqpoll])+
done
(*Kunen: "... so the order type <= K" *)
lemma ordertype_csquare_le:
"[| InfCard(K); ALL y:K. InfCard(y) --> y |*| y = y |]
==> ordertype(K*K, csquare_rel(K)) le K"
apply (frule InfCard_is_Card [THEN Card_is_Ord])
apply (rule all_lt_imp_le, assumption)
apply (erule well_ord_csquare [THEN Ord_ordertype])
apply (rule Card_lt_imp_lt)
apply (erule_tac [3] InfCard_is_Card)
apply (erule_tac [2] ltE)
apply (simp add: ordertype_unfold)
apply (safe elim!: ltE)
apply (subgoal_tac "Ord (xa) & Ord (ya)")
prefer 2 apply (blast intro: Ord_in_Ord, clarify)
(*??WHAT A MESS!*)
apply (rule InfCard_is_Limit [THEN ordermap_csquare_le, THEN lt_trans1],
(assumption | rule refl | erule ltI)+)
apply (rule_tac i = "xa Un ya" and j = nat in Ord_linear2,
simp_all add: Ord_Un Ord_nat)
prefer 2 (*case nat le (xa Un ya) *)
apply (simp add: le_imp_subset [THEN nat_succ_eqpoll, THEN cardinal_cong]
le_succ_iff InfCard_def Card_cardinal Un_least_lt Ord_Un
ltI nat_le_cardinal Ord_cardinal_le [THEN lt_trans1, THEN ltD])
(*the finite case: xa Un ya < nat *)
apply (rule_tac j = nat in lt_trans2)
apply (simp add: lt_def nat_cmult_eq_mult nat_succI mult_type
nat_into_Card [THEN Card_cardinal_eq] Ord_nat)
apply (simp add: InfCard_def)
done
(*Main result: Kunen's Theorem 10.12*)
lemma InfCard_csquare_eq: "InfCard(K) ==> K |*| K = K"
apply (frule InfCard_is_Card [THEN Card_is_Ord])
apply (erule rev_mp)
apply (erule_tac i=K in trans_induct)
apply (rule impI)
apply (rule le_anti_sym)
apply (erule_tac [2] InfCard_is_Card [THEN cmult_square_le])
apply (rule ordertype_csquare_le [THEN [2] le_trans])
apply (simp add: cmult_def Ord_cardinal_le
well_ord_csquare [THEN Ord_ordertype]
well_ord_csquare [THEN ordermap_bij, THEN bij_imp_eqpoll,
THEN cardinal_cong], assumption+)
done
(*Corollary for arbitrary well-ordered sets (all sets, assuming AC)*)
lemma well_ord_InfCard_square_eq:
"[| well_ord(A,r); InfCard(|A|) |] ==> A*A \<approx> A"
apply (rule prod_eqpoll_cong [THEN eqpoll_trans])
apply (erule well_ord_cardinal_eqpoll [THEN eqpoll_sym])+
apply (rule well_ord_cardinal_eqE)
apply (blast intro: Ord_cardinal well_ord_rmult well_ord_Memrel, assumption)
apply (simp add: cmult_def [symmetric] InfCard_csquare_eq)
done
lemma InfCard_square_eqpoll: "InfCard(K) ==> K \<times> K \<approx> K"
apply (rule well_ord_InfCard_square_eq)
apply (erule InfCard_is_Card [THEN Card_is_Ord, THEN well_ord_Memrel])
apply (simp add: InfCard_is_Card [THEN Card_cardinal_eq])
done
lemma Inf_Card_is_InfCard: "[| ~Finite(i); Card(i) |] ==> InfCard(i)"
by (simp add: InfCard_def Card_is_Ord [THEN nat_le_infinite_Ord])
subsubsection{*Toward's Kunen's Corollary 10.13 (1)*}
lemma InfCard_le_cmult_eq: "[| InfCard(K); L le K; 0<L |] ==> K |*| L = K"
apply (rule le_anti_sym)
prefer 2
apply (erule ltE, blast intro: cmult_le_self InfCard_is_Card)
apply (frule InfCard_is_Card [THEN Card_is_Ord, THEN le_refl])
apply (rule cmult_le_mono [THEN le_trans], assumption+)
apply (simp add: InfCard_csquare_eq)
done
(*Corollary 10.13 (1), for cardinal multiplication*)
lemma InfCard_cmult_eq: "[| InfCard(K); InfCard(L) |] ==> K |*| L = K Un L"
apply (rule_tac i = K and j = L in Ord_linear_le)
apply (typecheck add: InfCard_is_Card Card_is_Ord)
apply (rule cmult_commute [THEN ssubst])
apply (rule Un_commute [THEN ssubst])
apply (simp_all add: InfCard_is_Limit [THEN Limit_has_0] InfCard_le_cmult_eq
subset_Un_iff2 [THEN iffD1] le_imp_subset)
done
lemma InfCard_cdouble_eq: "InfCard(K) ==> K |+| K = K"
apply (simp add: cmult_2 [symmetric] InfCard_is_Card cmult_commute)
apply (simp add: InfCard_le_cmult_eq InfCard_is_Limit Limit_has_0 Limit_has_succ)
done
(*Corollary 10.13 (1), for cardinal addition*)
lemma InfCard_le_cadd_eq: "[| InfCard(K); L le K |] ==> K |+| L = K"
apply (rule le_anti_sym)
prefer 2
apply (erule ltE, blast intro: cadd_le_self InfCard_is_Card)
apply (frule InfCard_is_Card [THEN Card_is_Ord, THEN le_refl])
apply (rule cadd_le_mono [THEN le_trans], assumption+)
apply (simp add: InfCard_cdouble_eq)
done
lemma InfCard_cadd_eq: "[| InfCard(K); InfCard(L) |] ==> K |+| L = K Un L"
apply (rule_tac i = K and j = L in Ord_linear_le)
apply (typecheck add: InfCard_is_Card Card_is_Ord)
apply (rule cadd_commute [THEN ssubst])
apply (rule Un_commute [THEN ssubst])
apply (simp_all add: InfCard_le_cadd_eq subset_Un_iff2 [THEN iffD1] le_imp_subset)
done
(*The other part, Corollary 10.13 (2), refers to the cardinality of the set
of all n-tuples of elements of K. A better version for the Isabelle theory
might be InfCard(K) ==> |list(K)| = K.
*)
subsection{*For Every Cardinal Number There Exists A Greater One*}
text{*This result is Kunen's Theorem 10.16, which would be trivial using AC*}
lemma Ord_jump_cardinal: "Ord(jump_cardinal(K))"
apply (unfold jump_cardinal_def)
apply (rule Ord_is_Transset [THEN [2] OrdI])
prefer 2 apply (blast intro!: Ord_ordertype)
apply (unfold Transset_def)
apply (safe del: subsetI)
apply (simp add: ordertype_pred_unfold, safe)
apply (rule UN_I)
apply (rule_tac [2] ReplaceI)
prefer 4 apply (blast intro: well_ord_subset elim!: predE)+
done
(*Allows selective unfolding. Less work than deriving intro/elim rules*)
lemma jump_cardinal_iff:
"i : jump_cardinal(K) <->
(EX r X. r <= K*K & X <= K & well_ord(X,r) & i = ordertype(X,r))"
apply (unfold jump_cardinal_def)
apply (blast del: subsetI)
done
(*The easy part of Theorem 10.16: jump_cardinal(K) exceeds K*)
lemma K_lt_jump_cardinal: "Ord(K) ==> K < jump_cardinal(K)"
apply (rule Ord_jump_cardinal [THEN [2] ltI])
apply (rule jump_cardinal_iff [THEN iffD2])
apply (rule_tac x="Memrel(K)" in exI)
apply (rule_tac x=K in exI)
apply (simp add: ordertype_Memrel well_ord_Memrel)
apply (simp add: Memrel_def subset_iff)
done
(*The proof by contradiction: the bijection f yields a wellordering of X
whose ordertype is jump_cardinal(K). *)
lemma Card_jump_cardinal_lemma:
"[| well_ord(X,r); r <= K * K; X <= K;
f : bij(ordertype(X,r), jump_cardinal(K)) |]
==> jump_cardinal(K) : jump_cardinal(K)"
apply (subgoal_tac "f O ordermap (X,r) : bij (X, jump_cardinal (K))")
prefer 2 apply (blast intro: comp_bij ordermap_bij)
apply (rule jump_cardinal_iff [THEN iffD2])
apply (intro exI conjI)
apply (rule subset_trans [OF rvimage_type Sigma_mono], assumption+)
apply (erule bij_is_inj [THEN well_ord_rvimage])
apply (rule Ord_jump_cardinal [THEN well_ord_Memrel])
apply (simp add: well_ord_Memrel [THEN [2] bij_ordertype_vimage]
ordertype_Memrel Ord_jump_cardinal)
done
(*The hard part of Theorem 10.16: jump_cardinal(K) is itself a cardinal*)
lemma Card_jump_cardinal: "Card(jump_cardinal(K))"
apply (rule Ord_jump_cardinal [THEN CardI])
apply (unfold eqpoll_def)
apply (safe dest!: ltD jump_cardinal_iff [THEN iffD1])
apply (blast intro: Card_jump_cardinal_lemma [THEN mem_irrefl])
done
subsection{*Basic Properties of Successor Cardinals*}
lemma csucc_basic: "Ord(K) ==> Card(csucc(K)) & K < csucc(K)"
apply (unfold csucc_def)
apply (rule LeastI)
apply (blast intro: Card_jump_cardinal K_lt_jump_cardinal Ord_jump_cardinal)+
done
lemmas Card_csucc = csucc_basic [THEN conjunct1, standard]
lemmas lt_csucc = csucc_basic [THEN conjunct2, standard]
lemma Ord_0_lt_csucc: "Ord(K) ==> 0 < csucc(K)"
by (blast intro: Ord_0_le lt_csucc lt_trans1)
lemma csucc_le: "[| Card(L); K<L |] ==> csucc(K) le L"
apply (unfold csucc_def)
apply (rule Least_le)
apply (blast intro: Card_is_Ord)+
done
lemma lt_csucc_iff: "[| Ord(i); Card(K) |] ==> i < csucc(K) <-> |i| le K"
apply (rule iffI)
apply (rule_tac [2] Card_lt_imp_lt)
apply (erule_tac [2] lt_trans1)
apply (simp_all add: lt_csucc Card_csucc Card_is_Ord)
apply (rule notI [THEN not_lt_imp_le])
apply (rule Card_cardinal [THEN csucc_le, THEN lt_trans1, THEN lt_irrefl], assumption)
apply (rule Ord_cardinal_le [THEN lt_trans1])
apply (simp_all add: Ord_cardinal Card_is_Ord)
done
lemma Card_lt_csucc_iff:
"[| Card(K'); Card(K) |] ==> K' < csucc(K) <-> K' le K"
by (simp add: lt_csucc_iff Card_cardinal_eq Card_is_Ord)
lemma InfCard_csucc: "InfCard(K) ==> InfCard(csucc(K))"
by (simp add: InfCard_def Card_csucc Card_is_Ord
lt_csucc [THEN leI, THEN [2] le_trans])
subsubsection{*Removing elements from a finite set decreases its cardinality*}
lemma Fin_imp_not_cons_lepoll: "A: Fin(U) ==> x~:A --> ~ cons(x,A) \<lesssim> A"
apply (erule Fin_induct)
apply (simp add: lepoll_0_iff)
apply (subgoal_tac "cons (x,cons (xa,y)) = cons (xa,cons (x,y))")
apply simp
apply (blast dest!: cons_lepoll_consD, blast)
done
lemma Finite_imp_cardinal_cons [simp]:
"[| Finite(A); a~:A |] ==> |cons(a,A)| = succ(|A|)"
apply (unfold cardinal_def)
apply (rule Least_equality)
apply (fold cardinal_def)
apply (simp add: succ_def)
apply (blast intro: cons_eqpoll_cong well_ord_cardinal_eqpoll
elim!: mem_irrefl dest!: Finite_imp_well_ord)
apply (blast intro: Card_cardinal Card_is_Ord)
apply (rule notI)
apply (rule Finite_into_Fin [THEN Fin_imp_not_cons_lepoll, THEN mp, THEN notE],
assumption, assumption)
apply (erule eqpoll_sym [THEN eqpoll_imp_lepoll, THEN lepoll_trans])
apply (erule le_imp_lepoll [THEN lepoll_trans])
apply (blast intro: well_ord_cardinal_eqpoll [THEN eqpoll_imp_lepoll]
dest!: Finite_imp_well_ord)
done
lemma Finite_imp_succ_cardinal_Diff:
"[| Finite(A); a:A |] ==> succ(|A-{a}|) = |A|"
apply (rule_tac b = A in cons_Diff [THEN subst], assumption)
apply (simp add: Finite_imp_cardinal_cons Diff_subset [THEN subset_Finite])
apply (simp add: cons_Diff)
done
lemma Finite_imp_cardinal_Diff: "[| Finite(A); a:A |] ==> |A-{a}| < |A|"
apply (rule succ_leE)
apply (simp add: Finite_imp_succ_cardinal_Diff)
done
lemma Finite_cardinal_in_nat [simp]: "Finite(A) ==> |A| : nat"
apply (erule Finite_induct)
apply (auto simp add: cardinal_0 Finite_imp_cardinal_cons)
done
lemma card_Un_Int:
"[|Finite(A); Finite(B)|] ==> |A| #+ |B| = |A Un B| #+ |A Int B|"
apply (erule Finite_induct, simp)
apply (simp add: Finite_Int cons_absorb Un_cons Int_cons_left)
done
lemma card_Un_disjoint:
"[|Finite(A); Finite(B); A Int B = 0|] ==> |A Un B| = |A| #+ |B|"
by (simp add: Finite_Un card_Un_Int)
lemma card_partition [rule_format]:
"Finite(C) ==>
Finite (\<Union> C) -->
(\<forall>c\<in>C. |c| = k) -->
(\<forall>c1 \<in> C. \<forall>c2 \<in> C. c1 \<noteq> c2 --> c1 \<inter> c2 = 0) -->
k #* |C| = |\<Union> C|"
apply (erule Finite_induct, auto)
apply (subgoal_tac " x \<inter> \<Union>B = 0")
apply (auto simp add: card_Un_disjoint Finite_Union
subset_Finite [of _ "\<Union> (cons(x,F))"])
done
subsubsection{*Theorems by Krzysztof Grabczewski, proofs by lcp*}
lemmas nat_implies_well_ord = nat_into_Ord [THEN well_ord_Memrel, standard]
lemma nat_sum_eqpoll_sum: "[| m:nat; n:nat |] ==> m + n \<approx> m #+ n"
apply (rule eqpoll_trans)
apply (rule well_ord_radd [THEN well_ord_cardinal_eqpoll, THEN eqpoll_sym])
apply (erule nat_implies_well_ord)+
apply (simp add: nat_cadd_eq_add [symmetric] cadd_def eqpoll_refl)
done
lemma Ord_subset_natD [rule_format]: "Ord(i) ==> i <= nat --> i : nat | i=nat"
apply (erule trans_induct3, auto)
apply (blast dest!: nat_le_Limit [THEN le_imp_subset])
done
lemma Ord_nat_subset_into_Card: "[| Ord(i); i <= nat |] ==> Card(i)"
by (blast dest: Ord_subset_natD intro: Card_nat nat_into_Card)
lemma Finite_Diff_sing_eq_diff_1: "[| Finite(A); x:A |] ==> |A-{x}| = |A| #- 1"
apply (rule succ_inject)
apply (rule_tac b = "|A|" in trans)
apply (simp add: Finite_imp_succ_cardinal_Diff)
apply (subgoal_tac "1 \<lesssim> A")
prefer 2 apply (blast intro: not_0_is_lepoll_1)
apply (frule Finite_imp_well_ord, clarify)
apply (drule well_ord_lepoll_imp_Card_le)
apply (auto simp add: cardinal_1)
apply (rule trans)
apply (rule_tac [2] diff_succ)
apply (auto simp add: Finite_cardinal_in_nat)
done
lemma cardinal_lt_imp_Diff_not_0 [rule_format]:
"Finite(B) ==> ALL A. |B|<|A| --> A - B ~= 0"
apply (erule Finite_induct, auto)
apply (case_tac "Finite (A)")
apply (subgoal_tac [2] "Finite (cons (x, B))")
apply (drule_tac [2] B = "cons (x, B) " in Diff_Finite)
apply (auto simp add: Finite_0 Finite_cons)
apply (subgoal_tac "|B|<|A|")
prefer 2 apply (blast intro: lt_trans Ord_cardinal)
apply (case_tac "x:A")
apply (subgoal_tac [2] "A - cons (x, B) = A - B")
apply auto
apply (subgoal_tac "|A| le |cons (x, B) |")
prefer 2
apply (blast dest: Finite_cons [THEN Finite_imp_well_ord]
intro: well_ord_lepoll_imp_Card_le subset_imp_lepoll)
apply (auto simp add: Finite_imp_cardinal_cons)
apply (auto dest!: Finite_cardinal_in_nat simp add: le_iff)
apply (blast intro: lt_trans)
done
ML{*
val InfCard_def = @{thm InfCard_def};
val cmult_def = @{thm cmult_def};
val cadd_def = @{thm cadd_def};
val jump_cardinal_def = @{thm jump_cardinal_def};
val csucc_def = @{thm csucc_def};
val sum_commute_eqpoll = @{thm sum_commute_eqpoll};
val cadd_commute = @{thm cadd_commute};
val sum_assoc_eqpoll = @{thm sum_assoc_eqpoll};
val well_ord_cadd_assoc = @{thm well_ord_cadd_assoc};
val sum_0_eqpoll = @{thm sum_0_eqpoll};
val cadd_0 = @{thm cadd_0};
val sum_lepoll_self = @{thm sum_lepoll_self};
val cadd_le_self = @{thm cadd_le_self};
val sum_lepoll_mono = @{thm sum_lepoll_mono};
val cadd_le_mono = @{thm cadd_le_mono};
val eq_imp_not_mem = @{thm eq_imp_not_mem};
val sum_succ_eqpoll = @{thm sum_succ_eqpoll};
val nat_cadd_eq_add = @{thm nat_cadd_eq_add};
val prod_commute_eqpoll = @{thm prod_commute_eqpoll};
val cmult_commute = @{thm cmult_commute};
val prod_assoc_eqpoll = @{thm prod_assoc_eqpoll};
val well_ord_cmult_assoc = @{thm well_ord_cmult_assoc};
val sum_prod_distrib_eqpoll = @{thm sum_prod_distrib_eqpoll};
val well_ord_cadd_cmult_distrib = @{thm well_ord_cadd_cmult_distrib};
val prod_0_eqpoll = @{thm prod_0_eqpoll};
val cmult_0 = @{thm cmult_0};
val prod_singleton_eqpoll = @{thm prod_singleton_eqpoll};
val cmult_1 = @{thm cmult_1};
val prod_lepoll_self = @{thm prod_lepoll_self};
val cmult_le_self = @{thm cmult_le_self};
val prod_lepoll_mono = @{thm prod_lepoll_mono};
val cmult_le_mono = @{thm cmult_le_mono};
val prod_succ_eqpoll = @{thm prod_succ_eqpoll};
val nat_cmult_eq_mult = @{thm nat_cmult_eq_mult};
val cmult_2 = @{thm cmult_2};
val sum_lepoll_prod = @{thm sum_lepoll_prod};
val lepoll_imp_sum_lepoll_prod = @{thm lepoll_imp_sum_lepoll_prod};
val nat_cons_lepoll = @{thm nat_cons_lepoll};
val nat_cons_eqpoll = @{thm nat_cons_eqpoll};
val nat_succ_eqpoll = @{thm nat_succ_eqpoll};
val InfCard_nat = @{thm InfCard_nat};
val InfCard_is_Card = @{thm InfCard_is_Card};
val InfCard_Un = @{thm InfCard_Un};
val InfCard_is_Limit = @{thm InfCard_is_Limit};
val ordermap_eqpoll_pred = @{thm ordermap_eqpoll_pred};
val ordermap_z_lt = @{thm ordermap_z_lt};
val InfCard_le_cmult_eq = @{thm InfCard_le_cmult_eq};
val InfCard_cmult_eq = @{thm InfCard_cmult_eq};
val InfCard_cdouble_eq = @{thm InfCard_cdouble_eq};
val InfCard_le_cadd_eq = @{thm InfCard_le_cadd_eq};
val InfCard_cadd_eq = @{thm InfCard_cadd_eq};
val Ord_jump_cardinal = @{thm Ord_jump_cardinal};
val jump_cardinal_iff = @{thm jump_cardinal_iff};
val K_lt_jump_cardinal = @{thm K_lt_jump_cardinal};
val Card_jump_cardinal = @{thm Card_jump_cardinal};
val csucc_basic = @{thm csucc_basic};
val Card_csucc = @{thm Card_csucc};
val lt_csucc = @{thm lt_csucc};
val Ord_0_lt_csucc = @{thm Ord_0_lt_csucc};
val csucc_le = @{thm csucc_le};
val lt_csucc_iff = @{thm lt_csucc_iff};
val Card_lt_csucc_iff = @{thm Card_lt_csucc_iff};
val InfCard_csucc = @{thm InfCard_csucc};
val Finite_into_Fin = @{thm Finite_into_Fin};
val Fin_into_Finite = @{thm Fin_into_Finite};
val Finite_Fin_iff = @{thm Finite_Fin_iff};
val Finite_Un = @{thm Finite_Un};
val Finite_Union = @{thm Finite_Union};
val Finite_induct = @{thm Finite_induct};
val Fin_imp_not_cons_lepoll = @{thm Fin_imp_not_cons_lepoll};
val Finite_imp_cardinal_cons = @{thm Finite_imp_cardinal_cons};
val Finite_imp_succ_cardinal_Diff = @{thm Finite_imp_succ_cardinal_Diff};
val Finite_imp_cardinal_Diff = @{thm Finite_imp_cardinal_Diff};
val nat_implies_well_ord = @{thm nat_implies_well_ord};
val nat_sum_eqpoll_sum = @{thm nat_sum_eqpoll_sum};
val Diff_sing_Finite = @{thm Diff_sing_Finite};
val Diff_Finite = @{thm Diff_Finite};
val Ord_subset_natD = @{thm Ord_subset_natD};
val Ord_nat_subset_into_Card = @{thm Ord_nat_subset_into_Card};
val Finite_cardinal_in_nat = @{thm Finite_cardinal_in_nat};
val Finite_Diff_sing_eq_diff_1 = @{thm Finite_Diff_sing_eq_diff_1};
val cardinal_lt_imp_Diff_not_0 = @{thm cardinal_lt_imp_Diff_not_0};
*}
end