Statement List for Metamath Proof Explorer - 2101-2200 - Page 22 of 58
| Type | Label | Description |
| Statement |
| |
| Theorem | biopabd 2101 |
Equivalent wff's yield equal ordered-pair class abstractions (deduction
rule).
|
| ⊢
(φ → ∀xφ)
& ⊢ (φ → ∀yφ)
& ⊢ (φ → (ψ ↔ χ))
⇒ ⊢ (φ → {〈x, y〉∣ψ} = {〈x, y〉∣χ}) |
| |
| Theorem | biopabdv 2102 |
Equivalent wff's yield equal ordered-pair class abstractions (deduction
rule).
|
| ⊢
(φ → (ψ ↔ χ))
⇒ ⊢ (φ → {〈x, y〉∣ψ} = {〈x, y〉∣χ}) |
| |
| Theorem | biopabi 2103 |
Equivalent wff's yield equal class abstractions.
|
| ⊢
(φ ↔ ψ)
⇒ ⊢ {〈x, y〉∣φ} = {〈x, y〉∣ψ} |
| |
| Theorem | cbvopab 2104 |
Rule used to change bound variables in an ordered pair abstraction,
using implicit substitution.
|
| ⊢
(φ → ∀zφ)
& ⊢ (φ → ∀wφ)
& ⊢ (ψ → ∀xψ)
& ⊢ (ψ → ∀yψ)
& ⊢ ((x = z ∧
y = w)
→ (φ ↔ ψ))
⇒ ⊢ {〈x, y〉∣φ} = {〈z, w〉∣ψ} |
| |
| Theorem | cbvopabv 2105 |
Rule used to change bound variables in an ordered pair abstraction,
using implicit substitution.
|
| ⊢
((x = z ∧ y =
w) → (φ ↔ ψ))
⇒ ⊢ {〈x, y〉∣φ} = {〈z, w〉∣ψ} |
| |
| Theorem | cbvopab1 2106 |
Change first bound variable in an ordered pair abstraction,
using explicit substitution.
|
| ⊢
(φ → ∀zφ)
& ⊢ (ψ → ∀xψ)
& ⊢ (x = z →
(φ ↔ ψ))
⇒ ⊢ {〈x, y〉∣φ} = {〈z, y〉∣ψ} |
| |
| Theorem | cbvopab1s 2107 |
Change first bound variable in an ordered pair abstraction,
using explicit substitution.
|
| ⊢
{〈x, y〉∣φ} = {〈z, y〉∣[z / x]φ} |
| |
| Theorem | cbvopab1v 2108 |
Rule used to change the first bound variable in an ordered pair
abstraction, using implicit substitution.
|
| ⊢
(x = z → (φ
↔ ψ))
⇒ ⊢ {〈x, y〉∣φ} = {〈z, y〉∣ψ} |
| |
| Theorem | cbvopab2v 2109 |
Rule used to change the second bound variable in an ordered pair
abstraction, using implicit substitution.
|
| ⊢
(y = z → (φ
↔ ψ))
⇒ ⊢ {〈x, y〉∣φ} = {〈x, z〉∣ψ} |
| |
| Theorem | elopab 2110 |
Membership in a class abstraction of pairs.
|
| ⊢
(A ∈ {〈x, y〉∣φ} ↔ ∃x∃y(A =
〈x, y〉 ∧ φ)) |
| |
| Theorem | hbopab 2111 |
Bound-variable hypothesis builder for class abstraction.
|
| ⊢
(φ → ∀zφ)
⇒ ⊢ (w ∈ {〈x, y〉∣φ} → ∀z w ∈
{〈x, y〉∣φ}) |
| |
| Theorem | hbopab1 2112 |
The abstraction variables in a class abstraction of pairs are not
free.
|
| ⊢
(z ∈ {〈x, y〉∣φ} → ∀x z ∈
{〈x, y〉∣φ}) |
| |
| Theorem | hbopab2 2113 |
The abstraction variables in a class abstraction of pairs are not
free.
|
| ⊢
(z ∈ {〈x, y〉∣φ} → ∀y z ∈
{〈x, y〉∣φ}) |
| |
| Theorem | opabsb 2114 |
The law of concretion in terms of substitutions.
|
| ⊢
(〈z, w〉 ∈ {〈x, y〉∣φ} ↔ [w / y][z / x]φ) |
| |
| Theorem | opelopabg 2115 |
The law of concretion. Theorem 9.5 of [Quine]
p. 61.
|
| ⊢
(x = A → (φ
↔ ψ))
& ⊢ (y = B →
(ψ ↔ χ))
⇒ ⊢ ((A ∈ C
∧ B ∈ D) → (〈A, B〉
∈ {〈x, y〉∣φ} ↔ χ)) |
| |
| Theorem | brabg 2116 |
The law of concretion for a binary relation.
|
| ⊢
(x = A → (φ
↔ ψ))
& ⊢ (y = B →
(ψ ↔ χ))
& ⊢ R = {〈x,
y〉∣φ}
⇒ ⊢ ((A ∈ C
∧ B ∈ D) → (ARB ↔ χ)) |
| |
| Theorem | opelopab 2117 |
The law of concretion. Theorem 9.5 of [Quine]
p. 61.
|
| ⊢
A ∈ V
& ⊢ B ∈ V
& ⊢ (x = A →
(φ ↔ ψ))
& ⊢ (y = B →
(ψ ↔ χ))
⇒ ⊢ (〈A, B〉
∈ {〈x, y〉∣φ} ↔ χ) |
| |
| Theorem | brab 2118 |
The law of concretion for a binary relation.
|
| ⊢
A ∈ V
& ⊢ B ∈ V
& ⊢ (x = A →
(φ ↔ ψ))
& ⊢ (y = B →
(ψ ↔ χ))
& ⊢ R = {〈x,
y〉∣φ}
⇒ ⊢ (ARB ↔ χ) |
| |
| Theorem | ssopab2 2119 |
Equivalence of abstraction subclass and implication.
|
| ⊢
({〈x, y〉∣φ} ⊆ {〈x, y〉∣ψ} ↔ ∀x∀y(φ →
ψ)) |
| |
| Theorem | ssopab2i 2120 |
Inference of abstraction subclass from implication.
|
| ⊢
(φ → ψ)
⇒ ⊢ {〈x, y〉∣φ} ⊆ {〈x, y〉∣ψ} |
| |
| Theorem | unopab 2121 |
Union of two ordered pair class abstractions.
|
| ⊢
({〈x, y〉∣φ} ∪ {〈x, y〉∣ψ}) = {〈x, y〉∣(φ ∨ ψ)} |
| |
| Definition | df-eprel 2122 |
Define the epsilon relation. Similar to Definition 6.22 of
[TakeutiZaring] p. 30.
|
| ⊢
E = {〈x, y〉∣x
∈ y} |
| |
| Theorem | epelc 2123 |
The epsilon relation and the membership relation are the same.
|
| ⊢
A ∈ V
& ⊢ B ∈ V
⇒ ⊢ (AEB
↔ A ∈ B) |
| |
| Theorem | epel 2124 |
The epsilon relation and the membership relation are the same.
|
| ⊢
(xEy ↔ x
∈ y) |
| |
| Definition | df-id 2125 |
Define the identity relation. Definition 9.15 of [Quine] p. 64.
|
| ⊢
I = {〈x, y〉∣x
= y} |
| |
| Theorem | ideqg 2126 |
For sets, the identity relation is the same as equality.
|
| ⊢
((A ∈ C ∧ B
∈ D) → (AIB
↔ A = B)) |
| |
| Theorem | ideq 2127 |
For sets, the identity relation is the same as equality.
|
| ⊢
A ∈ V
& ⊢ B ∈ V
⇒ ⊢ (AIB
↔ A = B) |
| |
| Definition | df-po 2128 |
Define a partial order relation. Definition of [Enderton] p. 168.
|
| ⊢
(R Po A ↔ ∀x ∈ A
∀y ∈ A ∀z
∈ A (¬ xRx ∧ ((xRy ∧ yRz) → xRz))) |
| |
| Theorem | poss 2129 |
Subset theorem for the partial ordering predicate.
|
| ⊢
(A ⊆ B → (R Po
B → R Po A)) |
| |
| Theorem | poeq1 2130 |
Equality theorem for partial ordering predicate.
|
| ⊢
(R = S → (R Po
A ↔ S Po A)) |
| |
| Theorem | poeq2 2131 |
Equality theorem for partial ordering predicate.
|
| ⊢
(A = B → (R Po
A ↔ R Po B)) |
| |
| Theorem | pocl 2132 |
Properties of partial order relation in class notation.
|
| ⊢
(R Po A → ((B
∈ A ∧ C ∈ A
∧ D ∈ A) → (¬ BRB ∧ ((BRC ∧ CRD) → BRD)))) |
| |
| Theorem | poirr 2133 |
A partial order relation is irreflexive.
|
| ⊢
((R Po A ∧ B
∈ A) → ¬ BRB) |
| |
| Theorem | potr 2134 |
A partial order relation is a transitive relation.
|
| ⊢
((R Po A ∧ (B
∈ A ∧ C ∈ A
∧ D ∈ A)) → ((BRC ∧ CRD) → BRD)) |
| |
| Theorem | po2nr 2135 |
A partial order relation has no 2-cycle loops.
|
| ⊢
((R Po A ∧ (B
∈ A ∧ C ∈ A))
→ ¬ (BRC ∧
CRB)) |
| |
| Theorem | po3nr 2136 |
A partial order relation has no 3-cycle loops.
|
| ⊢
((R Po A ∧ (B
∈ A ∧ C ∈ A
∧ D ∈ A)) → ¬ (BRC ∧ CRD ∧ DRB)) |
| |
| Theorem | po0 2137 |
Any relation is a partial ordering of the empty set.
|
| ⊢
R Po ∅ |
| |
| Definition | df-so 2138 |
Define a strict or linear order relation.
|
| ⊢
(R Or A ↔ (R Po
A ∧ ∀x ∈ A
∀y ∈ A (xRy ∨
x = y
∨ yRx))) |
| |
| Theorem | sopo 2139 |
A strict order is a partial order.
|
| ⊢
(R Or A → R Po
A) |
| |
| Theorem | soss 2140 |
Subset theorem for the strict ordering predicate.
|
| ⊢
(A ⊆ B → (R Or
B → R Or A)) |
| |
| Theorem | soeq1 2141 |
Equality theorem for the strict ordering predicate.
|
| ⊢
(R = S → (R Or
A ↔ S Or A)) |
| |
| Theorem | soeq2 2142 |
Equality theorem for the strict ordering predicate.
|
| ⊢
(A = B → (R Or
A ↔ R Or B)) |
| |
| Theorem | sonr 2143 |
A strict order relation is irreflexive.
|
| ⊢
((R Or A ∧ B
∈ A) → ¬ BRB) |
| |
| Theorem | sotr 2144 |
A strict order relation is a transitive relation.
|
| ⊢
((R Or A ∧ (B
∈ A ∧ C ∈ A
∧ D ∈ A)) → ((BRC ∧ CRD) → BRD)) |
| |
| Theorem | solin 2145 |
A strict order relation is linear (satisfies trichotomy).
|
| ⊢
((R Or A ∧ (B
∈ A ∧ C ∈ A))
→ (BRC ∨
B = C
∨ CRB)) |
| |
| Theorem | so2nr 2146 |
A strict order relation has no 2-cycle loops.
|
| ⊢
((R Or A ∧ (B
∈ A ∧ C ∈ A))
→ ¬ (BRC ∧
CRB)) |
| |
| Theorem | so3nr 2147 |
A strict order relation has no 3-cycle loops.
|
| ⊢
((R Or A ∧ (B
∈ A ∧ C ∈ A
∧ D ∈ A)) → ¬ (BRC ∧ CRD ∧ DRB)) |
| |
| Theorem | sotric 2148 |
A strict order relation satisfies strict trichotomy.
|
| ⊢
((R Or A ∧ (B
∈ A ∧ C ∈ A))
→ (BRC ↔ ¬
(B = C
∨ CRB))) |
| |
| Theorem | sotrieq 2149 |
Trichotomy law for strict order relation.
|
| ⊢
((R Or A ∧ (B
∈ A ∧ C ∈ A))
→ (B = C ↔ ¬ (BRC ∨ CRB))) |
| |
| Theorem | sotrieq2 2150 |
Trichotomy law for strict order relation.
|
| ⊢
((R Or A ∧ (B
∈ A ∧ C ∈ A))
→ (B = C ↔ (¬ BRC ∧ ¬ CRB))) |
| |
| Theorem | itlso 2151 |
A irreflexive, transitive, linear relation is a strict ordering.
|
| ⊢
(x ∈ A → ¬ xRx) & ⊢ ((x ∈
A ∧ y ∈ A
∧ z ∈ A) → ((xRy ∧ yRz) → xRz)) & ⊢ ((x ∈
A ∧ y ∈ A)
→ (xRy ∨
x = y
∨ yRx))
⇒ ⊢ R Or A |
| |
| Theorem | so 2152 |
Deduce strict ordering from its properties.
|
| ⊢
((x ∈ A ∧ y
∈ A ∧ z ∈ A)
→ ((xRy ↔ ¬
(x = y
∨ yRx)) ∧
((xRy ∧
yRz) →
xRz)))
⇒ ⊢ R Or A |
| |
| Theorem | so0 2153 |
Any relation is a strict ordering of the empty set.
|
| ⊢
R Or ∅ |
| |
| Definition | df-sup 2154 |
Define the supremum of class B. It is
meaningful when R
is a relation that strictly orders A
and when the supremum
exists. For example, R could be
'less than', A could be the
set of real numbers, and B could be
the set of all positive
reals whose square is less than 2; in this case the supremum is defined
as the square root of 2 per sqrval 4729.
|
| ⊢
sup(B, A, R) = ∪{x ∈ A∣(∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz))} |
| |
| Theorem | supeq1 2155 |
Equality theorem for supremum.
|
| ⊢
(B = C → sup(B,
A, R)
= sup(C, A, R)) |
| |
| Theorem | supmo 2156 |
Any class B has at most one supremum in
A (where R is
interpreted as 'less than').
|
| ⊢
R Or A ⇒ ⊢ ∃*x(x ∈
A ∧ (∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz))) |
| |
| Theorem | supex 2157 |
A supremum is a set.
|
| ⊢
R Or A ⇒ ⊢ sup(B,
A, R)
∈ V |
| |
| Theorem | supeu 2158 |
A supremum is unique. Similar to Theorem I.26 of [Apostol] p. 24 (but
for supremums in general).
|
| ⊢
R Or A ⇒ ⊢ (∃x
∈ A (∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz)) →
∃!x ∈ A (∀y
∈ B ¬ xRy ∧ ∀y ∈ A
(yRx →
∃z ∈ B yRz))) |
| |
| Theorem | supcl 2159 |
A supremum belongs to its base class (closure law).
|
| ⊢
R Or A ⇒ ⊢ (∃x
∈ A (∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz)) →
sup(B, A, R) ∈
A) |
| |
| Theorem | supub 2160 |
A supremum is an upper bound.
|
| ⊢
R Or A ⇒ ⊢ (∃x
∈ A (∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz)) →
(C ∈ B → ¬ sup(B, A, R)RC)) |
| |
| Theorem | suplub 2161 |
A supremum is the least upper bound.
|
| ⊢
R Or A ⇒ ⊢ (∃x
∈ A (∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz)) →
((C ∈ A ∧ CRsup(B, A, R)) → ∃z ∈ B
CRz)) |
| |
| Theorem | supnub 2162 |
An upper bound is not less than the supremum.
|
| ⊢
R Or A ⇒ ⊢ (∃x
∈ A (∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz)) →
((C ∈ A ∧ ∀z ∈ B
¬ CRz) →
¬ CRsup(B,
A, R))) |
| |
| Theorem | supeui 2163 |
A supremum is unique. Similar to Theorem I.26 of [Apostol] p. 24 (but
for supremums in general).
|
| ⊢
R Or A & ⊢ ∃x
∈ A (∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz))
⇒ ⊢ ∃!x ∈ A
(∀y ∈ B ¬ xRy ∧ ∀y ∈ A
(yRx →
∃z ∈ B yRz)) |
| |
| Theorem | supcli 2164 |
A supremum belongs to its base class (closure law).
|
| ⊢
R Or A & ⊢ ∃x
∈ A (∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz))
⇒ ⊢ sup(B, A, R) ∈ A |
| |
| Theorem | supubi 2165 |
A supremum is an upper bound.
|
| ⊢
R Or A & ⊢ ∃x
∈ A (∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz))
⇒ ⊢ (C ∈ B
→ ¬ sup(B, A, R)RC) |
| |
| Theorem | suplubi 2166 |
A supremum is the least upper bound.
|
| ⊢
R Or A & ⊢ ∃x
∈ A (∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz))
⇒ ⊢ ((C ∈ A
∧ CRsup(B,
A, R))
→ ∃z ∈ B CRz) |
| |
| Theorem | supnubi 2167 |
An upper bound is not less than the supremum.
|
| ⊢
R Or A & ⊢ ∃x
∈ A (∀y ∈ B
¬ xRy ∧
∀y ∈ A (yRx →
∃z ∈ B yRz))
⇒ ⊢ ((C ∈ A
∧ ∀z ∈ B ¬ CRz) → ¬ CRsup(B, A, R)) |
| |
| Theorem | supsn 2168 |
The supremum of a singleton.
|
| ⊢
R Or A ⇒ ⊢ (B ∈
A → sup({B}, A, R) = B) |
| |
| Definition | df-fr 2169 |
Define a founded relation. For alternate definitions, see dffr2 2171 and
dffr3 2620.
|
| ⊢
(R Fr A ↔ ∀x((x ⊆
A ∧ ¬ x = ∅) → ∃y ∈ x
∀z ∈ x ¬ zRy)) |
| |
| Theorem | fri 2170 |
Property of founded relation (one direction of definition).
|
| ⊢
B ∈ V
⇒ ⊢ ((R Fr A ∧
(B ⊆ A ∧ ¬ B
= ∅)) → ∃x ∈
B ∀y ∈ B
¬ yRx) |
| |
| Theorem | dffr2 2171 |
Alternate definition of founded relation. Similar to Definition 6.21 of
[TakeutiZaring] p. 30.
|
| ⊢
(R Fr A ↔ ∀x((x ⊆
A ∧ ¬ x = ∅) → ∃y ∈ x
(x ∩ {z∣zRy}) = ∅)) |
| |
| Theorem | frc 2172 |
Property of founded relation (one direction of definition using class
variables).
|
| ⊢
B ∈ V
⇒ ⊢ (R Fr A →
((B ⊆ A ∧ ¬ B
= ∅) → ∃x ∈ B (B ∩
{y∣yRx}) = ∅)) |
| |
| Theorem | frss 2173 |
Subset theorem for the founded predicate. Exercise 1 of
[TakeutiZaring] p. 31.
|
| ⊢
(A ⊆ B → (R Fr
B → R Fr A)) |
| |
| Theorem | freq1 2174 |
Equality theorem for the founded predicate.
|
| ⊢
(R = S → (R Fr
A ↔ S Fr A)) |
| |
| Theorem | freq2 2175 |
Equality theorem for the founded predicate.
|
| ⊢
(A = B → (R Fr
A ↔ R Fr B)) |
| |
| Theorem | frirr 2176 |
A founded relation is irreflexive. Special case of Proposition 6.23 of
[TakeutiZaring] p. 30.
|
| ⊢
((R Fr A ∧ x
∈ A) → ¬ xRx) |
| |
| Theorem | fr2nr 2177 |
A founded relation has no 2-cycle loops. Special case of
Proposition 6.23 of [TakeutiZaring] p. 30.
|
| ⊢
((R Fr A ∧ (x
∈ A ∧ y ∈ A))
→ ¬ (xRy ∧
yRx)) |
| |
| Theorem | fr3nr 2178 |
A founded relation has no 3-cycle loops. Special case of
Proposition 6.23 of [TakeutiZaring] p. 30.
|
| ⊢
((R Fr A ∧ (x
∈ A ∧ y ∈ A
∧ z ∈ A)) → ¬ (xRy ∧ yRz ∧ zRx)) |
| |
| Theorem | fr0 2179 |
Any relation is founded on the empty set.
|
| ⊢
R Fr ∅ |
| |
| Theorem | efrirr 2180 |
Irreflexivitiy of the epsilon relation: a class founded by epsilon is
not a member of itself.
|
| ⊢
(E Fr A → ¬
A ∈ A) |
| |
| Theorem | efrn2lp 2181 |
A set founded by epsilon contains no 2-cycle loops.
|
| ⊢
((E Fr A ∧ (x ∈ A
∧ y ∈ A)) → ¬ (x ∈ y
∧ y ∈ x)) |
| |
| Theorem | epne3 2182 |
A set founded by epsilon contains no 3-cycle loops.
|
| ⊢
((E Fr A ∧ (x ∈ A
∧ y ∈ A ∧ z
∈ A)) → ¬ (x ∈ y
∧ y ∈ z ∧ z
∈ x)) |
| |
| Theorem | tz7.2 2183 |
Similar to Theorem 7.2 of [TakeutiZaring] p. 35, of except that the
Axiom of Regularity is not required due to antecedent E Fr A.
|
| ⊢
(((Tr A ∧ E Fr A) ∧ B
∈ A) → (B ⊆ A
∧ ¬ B = A)) |
| |
| Theorem | dfepfr 2184 |
A simpler way of saying that the epsilon relation is founded.
|
| ⊢
(E Fr A ↔
∀x((x ⊆ A
∧ ¬ x = ∅) →
∃y ∈ x (x ∩
y) = ∅)) |
| |
| Theorem | epfrc 2185 |
A subset of an epsilon-founded class has a minimal element.
|
| ⊢
B ∈ V
⇒ ⊢ ((E Fr
A ∧ (B ⊆ A
∧ ¬ B = ∅)) →
∃x ∈ B (B ∩
x) = ∅) |
| |
| Definition | df-we 2186 |
Define a well-ordering. For an alternate definition see dfwe2 2187.
|
| ⊢
(R We A ↔ (R Fr
A ∧ R Or A)) |
| |
| Theorem | dfwe2 2187 |
Alternate definition of well-ordering. Definition 6.24(2) of
[TakeutiZaring] p. 30.
|
| ⊢
(R We A ↔ (R Fr
A ∧ ∀x ∈ A
∀y ∈ A (xRy ∨
x = y
∨ yRx))) |
| |
| Theorem | wess 2188 |
Subset theorem for the well-ordering predicate. Exercise 4 of
[TakeutiZaring] p. 31.
|
| ⊢
(A ⊆ B → (R We
B → R We A)) |
| |
| Theorem | weeq1 2189 |
Equality theorem for the well-ordering predicate.
|
| ⊢
(R = S → (R We
A ↔ S We A)) |
| |
| Theorem | weeq2 2190 |
Equality theorem for the well-ordering predicate.
|
| ⊢
(A = B → (R We
A ↔ R We B)) |
| |
| Theorem | wefr 2191 |
A well-ordering is founded.
|
| ⊢
(R We A → R Fr
A) |
| |
| Theorem | weso 2192 |
A well-ordering is a strict ordering.
|
| ⊢
(R We A → R Or
A) |
| |
| Theorem | wecmpep 2193 |
The elements of an epsilon well-ordering are comparable.
|
| ⊢
((E We A ∧ (x ∈ A
∧ y ∈ A)) → (x
∈ y ∨ x = y ∨
y ∈ x)) |
| |
| Theorem | wetrep 2194 |
An epsilon well-ordering is a transitive relation.
|
| ⊢
((E We A ∧ (x ∈ A
∧ y ∈ A ∧ z
∈ A)) → ((x ∈ y
∧ y ∈ z) → x
∈ z)) |
| |
| Theorem | wefrc 2195 |
A non-empty (possibly proper) subclass of a class well-ordered by E
has a minimal element. Special case of Proposition 6.26 of
[TakeutiZaring] p. 31.
|
| ⊢
((E We A ∧ (B ⊆ A
∧ ¬ B = ∅)) →
∃x ∈ B (B ∩
x) = ∅) |
| |
| Theorem | we0 2196 |
Any relation is a well-ordering of the empty set.
|
| ⊢
R We ∅ |
| |
| Theorem | wereu 2197 |
A subset of a well-ordered set has a unique minimal element.
|
| ⊢
B ∈ V
⇒ ⊢ ((R We A ∧
(B ⊆ A ∧ ¬ B
= ∅)) → ∃!x ∈
B ∀y ∈ B
¬ yRx) |
| |
| Syntax | word 2198 |
Extend the definition of a wff to include the ordinal predicate.
|
| wff Ord
A |
| |
| Syntax | con0 2199 |
Extend the definition of a class to include the class of all ordinals.
(The 0 in the name prevents creating a file called con.html, which
causes problems in Windows.)
|
| class
On |
| |
| Syntax | wlim 2200 |
Extend the definition of a wff to include the limit ordinal predicate.
|
| wff Lim
A |