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Type | Label | Description |
---|---|---|
Statement | ||
Theorem | disjcsn 9601 | A class is disjoint from its singleton. A consequence of regularity. (Contributed by Jonathan Ben-Naim, 3-Jun-2011.) (Revised by BJ, 4-Apr-2019.) |
⊢ (𝐴 ∩ {𝐴}) = ∅ | ||
Theorem | zfregfr 9602 | The membership relation is well-founded on any class. (Contributed by NM, 26-Nov-1995.) |
⊢ E Fr 𝐴 | ||
Theorem | en2lp 9603 | No class has 2-cycle membership loops. Theorem 7X(b) of [Enderton] p. 206. (Contributed by NM, 16-Oct-1996.) (Revised by Mario Carneiro, 25-Jun-2015.) |
⊢ ¬ (𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐴) | ||
Theorem | elnanel 9604 | Two classes are not elements of each other simultaneously. This is just a rewriting of en2lp 9603 and serves as an example in the context of Godel codes, see elnanelprv 34489. (Contributed by AV, 5-Nov-2023.) (New usage is discouraged.) |
⊢ (𝐴 ∈ 𝐵 ⊼ 𝐵 ∈ 𝐴) | ||
Theorem | cnvepnep 9605 | The membership (epsilon) relation and its converse are disjoint, i.e., E is an asymmetric relation. Variable-free version of en2lp 9603. (Proposed by BJ, 18-Jun-2022.) (Contributed by AV, 19-Jun-2022.) |
⊢ (◡ E ∩ E ) = ∅ | ||
Theorem | epnsym 9606 | The membership (epsilon) relation is not symmetric. (Contributed by AV, 18-Jun-2022.) |
⊢ ◡ E ≠ E | ||
Theorem | elnotel 9607 | A class cannot be an element of one of its elements. (Contributed by AV, 14-Jun-2022.) |
⊢ (𝐴 ∈ 𝐵 → ¬ 𝐵 ∈ 𝐴) | ||
Theorem | elnel 9608 | A class cannot be an element of one of its elements. (Contributed by AV, 14-Jun-2022.) |
⊢ (𝐴 ∈ 𝐵 → 𝐵 ∉ 𝐴) | ||
Theorem | en3lplem1 9609* | Lemma for en3lp 9611. (Contributed by Alan Sare, 28-Oct-2011.) |
⊢ ((𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴) → (𝑥 = 𝐴 → (𝑥 ∩ {𝐴, 𝐵, 𝐶}) ≠ ∅)) | ||
Theorem | en3lplem2 9610* | Lemma for en3lp 9611. (Contributed by Alan Sare, 28-Oct-2011.) |
⊢ ((𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴) → (𝑥 ∈ {𝐴, 𝐵, 𝐶} → (𝑥 ∩ {𝐴, 𝐵, 𝐶}) ≠ ∅)) | ||
Theorem | en3lp 9611 | No class has 3-cycle membership loops. This proof was automatically generated from the virtual deduction proof en3lpVD 43694 using a translation program. (Contributed by Alan Sare, 24-Oct-2011.) |
⊢ ¬ (𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴) | ||
Theorem | preleqg 9612 | Equality of two unordered pairs when one member of each pair contains the other member. Closed form of preleq 9613. (Contributed by AV, 15-Jun-2022.) |
⊢ (((𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝑉 ∧ 𝐶 ∈ 𝐷) ∧ {𝐴, 𝐵} = {𝐶, 𝐷}) → (𝐴 = 𝐶 ∧ 𝐵 = 𝐷)) | ||
Theorem | preleq 9613 | Equality of two unordered pairs when one member of each pair contains the other member. (Contributed by NM, 16-Oct-1996.) (Revised by AV, 15-Jun-2022.) |
⊢ 𝐵 ∈ V ⇒ ⊢ (((𝐴 ∈ 𝐵 ∧ 𝐶 ∈ 𝐷) ∧ {𝐴, 𝐵} = {𝐶, 𝐷}) → (𝐴 = 𝐶 ∧ 𝐵 = 𝐷)) | ||
Theorem | preleqALT 9614 | Alternate proof of preleq 9613, not based on preleqg 9612: Equality of two unordered pairs when one member of each pair contains the other member. (Contributed by NM, 16-Oct-1996.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ 𝐵 ∈ V & ⊢ 𝐷 ∈ V ⇒ ⊢ (((𝐴 ∈ 𝐵 ∧ 𝐶 ∈ 𝐷) ∧ {𝐴, 𝐵} = {𝐶, 𝐷}) → (𝐴 = 𝐶 ∧ 𝐵 = 𝐷)) | ||
Theorem | opthreg 9615 | Theorem for alternate representation of ordered pairs, requiring the Axiom of Regularity ax-reg 9589 (via the preleq 9613 step). See df-op 4635 for a description of other ordered pair representations. Exercise 34 of [Enderton] p. 207. (Contributed by NM, 16-Oct-1996.) (Proof shortened by AV, 15-Jun-2022.) |
⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V & ⊢ 𝐶 ∈ V & ⊢ 𝐷 ∈ V ⇒ ⊢ ({𝐴, {𝐴, 𝐵}} = {𝐶, {𝐶, 𝐷}} ↔ (𝐴 = 𝐶 ∧ 𝐵 = 𝐷)) | ||
Theorem | suc11reg 9616 | The successor operation behaves like a one-to-one function (assuming the Axiom of Regularity). Exercise 35 of [Enderton] p. 208 and its converse. (Contributed by NM, 25-Oct-2003.) |
⊢ (suc 𝐴 = suc 𝐵 ↔ 𝐴 = 𝐵) | ||
Theorem | dford2 9617* | Assuming ax-reg 9589, an ordinal is a transitive class on which inclusion satisfies trichotomy. (Contributed by Scott Fenton, 27-Oct-2010.) |
⊢ (Ord 𝐴 ↔ (Tr 𝐴 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥 ∈ 𝑦 ∨ 𝑥 = 𝑦 ∨ 𝑦 ∈ 𝑥))) | ||
Theorem | inf0 9618* | Existence of ω implies our axiom of infinity ax-inf 9635. The proof shows that the especially contrived class "ran (rec((𝑣 ∈ V ↦ suc 𝑣), 𝑥) ↾ ω) " exists, is a subset of its union, and contains a given set 𝑥 (and thus is nonempty). Thus, it provides an example demonstrating that a set 𝑦 exists with the necessary properties demanded by ax-inf 9635. (Contributed by NM, 15-Oct-1996.) Revised to closed form. (Revised by BJ, 20-May-2024.) |
⊢ (ω ∈ 𝑉 → ∃𝑦(𝑥 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∃𝑤(𝑧 ∈ 𝑤 ∧ 𝑤 ∈ 𝑦)))) | ||
Theorem | inf1 9619 | Variation of Axiom of Infinity (using zfinf 9636 as a hypothesis). Axiom of Infinity in [FreydScedrov] p. 283. (Contributed by NM, 14-Oct-1996.) (Revised by David Abernethy, 1-Oct-2013.) |
⊢ ∃𝑥(𝑦 ∈ 𝑥 ∧ ∀𝑦(𝑦 ∈ 𝑥 → ∃𝑧(𝑦 ∈ 𝑧 ∧ 𝑧 ∈ 𝑥))) ⇒ ⊢ ∃𝑥(𝑥 ≠ ∅ ∧ ∀𝑦(𝑦 ∈ 𝑥 → ∃𝑧(𝑦 ∈ 𝑧 ∧ 𝑧 ∈ 𝑥))) | ||
Theorem | inf2 9620* | Variation of Axiom of Infinity. There exists a nonempty set that is a subset of its union (using zfinf 9636 as a hypothesis). Abbreviated version of the Axiom of Infinity in [FreydScedrov] p. 283. (Contributed by NM, 28-Oct-1996.) |
⊢ ∃𝑥(𝑦 ∈ 𝑥 ∧ ∀𝑦(𝑦 ∈ 𝑥 → ∃𝑧(𝑦 ∈ 𝑧 ∧ 𝑧 ∈ 𝑥))) ⇒ ⊢ ∃𝑥(𝑥 ≠ ∅ ∧ 𝑥 ⊆ ∪ 𝑥) | ||
Theorem | inf3lema 9621* | Lemma for our Axiom of Infinity => standard Axiom of Infinity. See inf3 9632 for detailed description. (Contributed by NM, 28-Oct-1996.) |
⊢ 𝐺 = (𝑦 ∈ V ↦ {𝑤 ∈ 𝑥 ∣ (𝑤 ∩ 𝑥) ⊆ 𝑦}) & ⊢ 𝐹 = (rec(𝐺, ∅) ↾ ω) & ⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ (𝐴 ∈ (𝐺‘𝐵) ↔ (𝐴 ∈ 𝑥 ∧ (𝐴 ∩ 𝑥) ⊆ 𝐵)) | ||
Theorem | inf3lemb 9622* | Lemma for our Axiom of Infinity => standard Axiom of Infinity. See inf3 9632 for detailed description. (Contributed by NM, 28-Oct-1996.) |
⊢ 𝐺 = (𝑦 ∈ V ↦ {𝑤 ∈ 𝑥 ∣ (𝑤 ∩ 𝑥) ⊆ 𝑦}) & ⊢ 𝐹 = (rec(𝐺, ∅) ↾ ω) & ⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ (𝐹‘∅) = ∅ | ||
Theorem | inf3lemc 9623* | Lemma for our Axiom of Infinity => standard Axiom of Infinity. See inf3 9632 for detailed description. (Contributed by NM, 28-Oct-1996.) |
⊢ 𝐺 = (𝑦 ∈ V ↦ {𝑤 ∈ 𝑥 ∣ (𝑤 ∩ 𝑥) ⊆ 𝑦}) & ⊢ 𝐹 = (rec(𝐺, ∅) ↾ ω) & ⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ (𝐴 ∈ ω → (𝐹‘suc 𝐴) = (𝐺‘(𝐹‘𝐴))) | ||
Theorem | inf3lemd 9624* | Lemma for our Axiom of Infinity => standard Axiom of Infinity. See inf3 9632 for detailed description. (Contributed by NM, 28-Oct-1996.) |
⊢ 𝐺 = (𝑦 ∈ V ↦ {𝑤 ∈ 𝑥 ∣ (𝑤 ∩ 𝑥) ⊆ 𝑦}) & ⊢ 𝐹 = (rec(𝐺, ∅) ↾ ω) & ⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ (𝐴 ∈ ω → (𝐹‘𝐴) ⊆ 𝑥) | ||
Theorem | inf3lem1 9625* | Lemma for our Axiom of Infinity => standard Axiom of Infinity. See inf3 9632 for detailed description. (Contributed by NM, 28-Oct-1996.) |
⊢ 𝐺 = (𝑦 ∈ V ↦ {𝑤 ∈ 𝑥 ∣ (𝑤 ∩ 𝑥) ⊆ 𝑦}) & ⊢ 𝐹 = (rec(𝐺, ∅) ↾ ω) & ⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ (𝐴 ∈ ω → (𝐹‘𝐴) ⊆ (𝐹‘suc 𝐴)) | ||
Theorem | inf3lem2 9626* | Lemma for our Axiom of Infinity => standard Axiom of Infinity. See inf3 9632 for detailed description. (Contributed by NM, 28-Oct-1996.) |
⊢ 𝐺 = (𝑦 ∈ V ↦ {𝑤 ∈ 𝑥 ∣ (𝑤 ∩ 𝑥) ⊆ 𝑦}) & ⊢ 𝐹 = (rec(𝐺, ∅) ↾ ω) & ⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ ((𝑥 ≠ ∅ ∧ 𝑥 ⊆ ∪ 𝑥) → (𝐴 ∈ ω → (𝐹‘𝐴) ≠ 𝑥)) | ||
Theorem | inf3lem3 9627* | Lemma for our Axiom of Infinity => standard Axiom of Infinity. See inf3 9632 for detailed description. In the proof, we invoke the Axiom of Regularity in the form of zfreg 9592. (Contributed by NM, 29-Oct-1996.) |
⊢ 𝐺 = (𝑦 ∈ V ↦ {𝑤 ∈ 𝑥 ∣ (𝑤 ∩ 𝑥) ⊆ 𝑦}) & ⊢ 𝐹 = (rec(𝐺, ∅) ↾ ω) & ⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ ((𝑥 ≠ ∅ ∧ 𝑥 ⊆ ∪ 𝑥) → (𝐴 ∈ ω → (𝐹‘𝐴) ≠ (𝐹‘suc 𝐴))) | ||
Theorem | inf3lem4 9628* | Lemma for our Axiom of Infinity => standard Axiom of Infinity. See inf3 9632 for detailed description. (Contributed by NM, 29-Oct-1996.) |
⊢ 𝐺 = (𝑦 ∈ V ↦ {𝑤 ∈ 𝑥 ∣ (𝑤 ∩ 𝑥) ⊆ 𝑦}) & ⊢ 𝐹 = (rec(𝐺, ∅) ↾ ω) & ⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ ((𝑥 ≠ ∅ ∧ 𝑥 ⊆ ∪ 𝑥) → (𝐴 ∈ ω → (𝐹‘𝐴) ⊊ (𝐹‘suc 𝐴))) | ||
Theorem | inf3lem5 9629* | Lemma for our Axiom of Infinity => standard Axiom of Infinity. See inf3 9632 for detailed description. (Contributed by NM, 29-Oct-1996.) |
⊢ 𝐺 = (𝑦 ∈ V ↦ {𝑤 ∈ 𝑥 ∣ (𝑤 ∩ 𝑥) ⊆ 𝑦}) & ⊢ 𝐹 = (rec(𝐺, ∅) ↾ ω) & ⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ ((𝑥 ≠ ∅ ∧ 𝑥 ⊆ ∪ 𝑥) → ((𝐴 ∈ ω ∧ 𝐵 ∈ 𝐴) → (𝐹‘𝐵) ⊊ (𝐹‘𝐴))) | ||
Theorem | inf3lem6 9630* | Lemma for our Axiom of Infinity => standard Axiom of Infinity. See inf3 9632 for detailed description. (Contributed by NM, 29-Oct-1996.) |
⊢ 𝐺 = (𝑦 ∈ V ↦ {𝑤 ∈ 𝑥 ∣ (𝑤 ∩ 𝑥) ⊆ 𝑦}) & ⊢ 𝐹 = (rec(𝐺, ∅) ↾ ω) & ⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ ((𝑥 ≠ ∅ ∧ 𝑥 ⊆ ∪ 𝑥) → 𝐹:ω–1-1→𝒫 𝑥) | ||
Theorem | inf3lem7 9631* | Lemma for our Axiom of Infinity => standard Axiom of Infinity. See inf3 9632 for detailed description. In the proof, we invoke the Axiom of Replacement in the form of f1dmex 7945. (Contributed by NM, 29-Oct-1996.) (Proof shortened by Mario Carneiro, 19-Jan-2013.) |
⊢ 𝐺 = (𝑦 ∈ V ↦ {𝑤 ∈ 𝑥 ∣ (𝑤 ∩ 𝑥) ⊆ 𝑦}) & ⊢ 𝐹 = (rec(𝐺, ∅) ↾ ω) & ⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ ((𝑥 ≠ ∅ ∧ 𝑥 ⊆ ∪ 𝑥) → ω ∈ V) | ||
Theorem | inf3 9632 |
Our Axiom of Infinity ax-inf 9635 implies the standard Axiom of Infinity.
The hypothesis is a variant of our Axiom of Infinity provided by
inf2 9620, and the conclusion is the version of the Axiom of Infinity
shown as Axiom 7 in [TakeutiZaring] p. 43. (Other standard versions are
proved later as axinf2 9637 and zfinf2 9639.) The main proof is provided by
inf3lema 9621 through inf3lem7 9631, and this final piece eliminates the
auxiliary hypothesis of inf3lem7 9631. This proof is due to
Ian Sutherland, Richard Heck, and Norman Megill and was posted
on Usenet as shown below. Although the result is not new, the authors
were unable to find a published proof.
(As posted to sci.logic on 30-Oct-1996, with annotations added.) Theorem: The statement "There exists a nonempty set that is a subset of its union" implies the Axiom of Infinity. Proof: Let X be a nonempty set which is a subset of its union; the latter property is equivalent to saying that for any y in X, there exists a z in X such that y is in z. Define by finite recursion a function F:omega-->(power X) such that F_0 = 0 (See inf3lemb 9622.) F_n+1 = {y<X | y^X subset F_n} (See inf3lemc 9623.) Note: ^ means intersect, < means \in ("element of"). (Finite recursion as typically done requires the existence of omega; to avoid this we can just use transfinite recursion restricted to omega. F is a class-term that is not necessarily a set at this point.) Lemma 1. F_n subset F_n+1. (See inf3lem1 9625.) Proof: By induction: F_0 subset F_1. If y < F_n+1, then y^X subset F_n, so if F_n subset F_n+1, then y^X subset F_n+1, so y < F_n+2. Lemma 2. F_n =/= X. (See inf3lem2 9626.) Proof: By induction: F_0 =/= X because X is not empty. Assume F_n =/= X. Then there is a y in X that is not in F_n. By definition of X, there is a z in X that contains y. Suppose F_n+1 = X. Then z is in F_n+1, and z^X contains y, so z^X is not a subset of F_n, contrary to the definition of F_n+1. Lemma 3. F_n =/= F_n+1. (See inf3lem3 9627.) Proof: Using the identity y^X subset F_n <-> y^(X-F_n) = 0, we have F_n+1 = {y<X | y^(X-F_n) = 0}. Let q = {y<X-F_n | y^(X-F_n) = 0}. Then q subset F_n+1. Since X-F_n is not empty by Lemma 2 and q is the set of \in-minimal elements of X-F_n, by Foundation q is not empty, so q and therefore F_n+1 have an element not in F_n. Lemma 4. F_n proper_subset F_n+1. (See inf3lem4 9628.) Proof: Lemmas 1 and 3. Lemma 5. F_m proper_subset F_n, m < n. (See inf3lem5 9629.) Proof: Fix m and use induction on n > m. Basis: F_m proper_subset F_m+1 by Lemma 4. Induction: Assume F_m proper_subset F_n. Then since F_n proper_subset F_n+1, F_m proper_subset F_n+1 by transitivity of proper subset. By Lemma 5, F_m =/= F_n for m =/= n, so F is 1-1. (See inf3lem6 9630.) Thus, the inverse of F is a function with range omega and domain a subset of power X, so omega exists by Replacement. (See inf3lem7 9631.) Q.E.D.(Contributed by NM, 29-Oct-1996.) |
⊢ ∃𝑥(𝑥 ≠ ∅ ∧ 𝑥 ⊆ ∪ 𝑥) ⇒ ⊢ ω ∈ V | ||
Theorem | infeq5i 9633 | Half of infeq5 9634. (Contributed by Mario Carneiro, 16-Nov-2014.) |
⊢ (ω ∈ V → ∃𝑥 𝑥 ⊊ ∪ 𝑥) | ||
Theorem | infeq5 9634 | The statement "there exists a set that is a proper subset of its union" is equivalent to the Axiom of Infinity (shown on the right-hand side in the form of omex 9640.) The left-hand side provides us with a very short way to express the Axiom of Infinity using only elementary symbols. This proof of equivalence does not depend on the Axiom of Infinity. (Contributed by NM, 23-Mar-2004.) (Revised by Mario Carneiro, 16-Nov-2014.) |
⊢ (∃𝑥 𝑥 ⊊ ∪ 𝑥 ↔ ω ∈ V) | ||
Axiom | ax-inf 9635* |
Axiom of Infinity. An axiom of Zermelo-Fraenkel set theory. This axiom
is the gateway to "Cantor's paradise" (an expression coined by
Hilbert).
It asserts that given a starting set 𝑥, an infinite set 𝑦 built
from it exists. Although our version is apparently not given in the
literature, it is similar to, but slightly shorter than, the Axiom of
Infinity in [FreydScedrov] p. 283
(see inf1 9619 and inf2 9620). More
standard versions, which essentially state that there exists a set
containing all the natural numbers, are shown as zfinf2 9639 and omex 9640 and
are based on the (nontrivial) proof of inf3 9632.
This version has the
advantage that when expanded to primitives, it has fewer symbols than
the standard version ax-inf2 9638. Theorem inf0 9618
shows the reverse
derivation of our axiom from a standard one. Theorem inf5 9642
shows a
very short way to state this axiom.
The standard version of Infinity ax-inf2 9638 requires this axiom along with Regularity ax-reg 9589 for its derivation (as Theorem axinf2 9637 below). In order to more easily identify the normal uses of Regularity, we will usually reference ax-inf2 9638 instead of this one. The derivation of this axiom from ax-inf2 9638 is shown by Theorem axinf 9641. Proofs should normally use the standard version ax-inf2 9638 instead of this axiom. (New usage is discouraged.) (Contributed by NM, 16-Aug-1993.) |
⊢ ∃𝑦(𝑥 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∃𝑤(𝑧 ∈ 𝑤 ∧ 𝑤 ∈ 𝑦))) | ||
Theorem | zfinf 9636* | Axiom of Infinity expressed with the fewest number of different variables. (New usage is discouraged.) (Contributed by NM, 14-Aug-2003.) |
⊢ ∃𝑥(𝑦 ∈ 𝑥 ∧ ∀𝑦(𝑦 ∈ 𝑥 → ∃𝑧(𝑦 ∈ 𝑧 ∧ 𝑧 ∈ 𝑥))) | ||
Theorem | axinf2 9637* |
A standard version of Axiom of Infinity, expanded to primitives, derived
from our version of Infinity ax-inf 9635 and Regularity ax-reg 9589.
This theorem should not be referenced in any proof. Instead, use ax-inf2 9638 below so that the ordinary uses of Regularity can be more easily identified. (New usage is discouraged.) (Contributed by NM, 3-Nov-1996.) |
⊢ ∃𝑥(∃𝑦(𝑦 ∈ 𝑥 ∧ ∀𝑧 ¬ 𝑧 ∈ 𝑦) ∧ ∀𝑦(𝑦 ∈ 𝑥 → ∃𝑧(𝑧 ∈ 𝑥 ∧ ∀𝑤(𝑤 ∈ 𝑧 ↔ (𝑤 ∈ 𝑦 ∨ 𝑤 = 𝑦))))) | ||
Axiom | ax-inf2 9638* | A standard version of Axiom of Infinity of ZF set theory. In English, it says: there exists a set that contains the empty set and the successors of all of its members. Theorem zfinf2 9639 shows it converted to abbreviations. This axiom was derived as Theorem axinf2 9637 above, using our version of Infinity ax-inf 9635 and the Axiom of Regularity ax-reg 9589. We will reference ax-inf2 9638 instead of axinf2 9637 so that the ordinary uses of Regularity can be more easily identified. The reverse derivation of ax-inf 9635 from ax-inf2 9638 is shown by Theorem axinf 9641. (Contributed by NM, 3-Nov-1996.) |
⊢ ∃𝑥(∃𝑦(𝑦 ∈ 𝑥 ∧ ∀𝑧 ¬ 𝑧 ∈ 𝑦) ∧ ∀𝑦(𝑦 ∈ 𝑥 → ∃𝑧(𝑧 ∈ 𝑥 ∧ ∀𝑤(𝑤 ∈ 𝑧 ↔ (𝑤 ∈ 𝑦 ∨ 𝑤 = 𝑦))))) | ||
Theorem | zfinf2 9639* | A standard version of the Axiom of Infinity, using definitions to abbreviate. Axiom Inf of [BellMachover] p. 472. (See ax-inf2 9638 for the unabbreviated version.) (Contributed by NM, 30-Aug-1993.) |
⊢ ∃𝑥(∅ ∈ 𝑥 ∧ ∀𝑦 ∈ 𝑥 suc 𝑦 ∈ 𝑥) | ||
Theorem | omex 9640 |
The existence of omega (the class of natural numbers). Axiom 7 of
[TakeutiZaring] p. 43. Remark
1.21 of [Schloeder] p. 3. This theorem
is proved assuming the Axiom of Infinity and in fact is equivalent to
it, as shown by the reverse derivation inf0 9618.
A finitist (someone who doesn't believe in infinity) could, without contradiction, replace the Axiom of Infinity by its denial ¬ ω ∈ V; this would lead to ω = On by omon 7869 and Fin = V (the universe of all sets) by fineqv 9265. The finitist could still develop natural number, integer, and rational number arithmetic but would be denied the real numbers (as well as much of the rest of mathematics). In deference to the finitist, much of our development is done, when possible, without invoking the Axiom of Infinity; an example is Peano's axioms peano1 7881 through peano5 7886 (which many textbooks prove more easily assuming Infinity). (Contributed by NM, 6-Aug-1994.) |
⊢ ω ∈ V | ||
Theorem | axinf 9641* | The first version of the Axiom of Infinity ax-inf 9635 proved from the second version ax-inf2 9638. Note that we didn't use ax-reg 9589, unlike the other direction axinf2 9637. (Contributed by NM, 24-Apr-2009.) |
⊢ ∃𝑦(𝑥 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∃𝑤(𝑧 ∈ 𝑤 ∧ 𝑤 ∈ 𝑦))) | ||
Theorem | inf5 9642 | The statement "there exists a set that is a proper subset of its union" is equivalent to the Axiom of Infinity (see Theorem infeq5 9634). This provides us with a very compact way to express the Axiom of Infinity using only elementary symbols. (Contributed by NM, 3-Jun-2005.) |
⊢ ∃𝑥 𝑥 ⊊ ∪ 𝑥 | ||
Theorem | omelon 9643 | Omega is an ordinal number. Theorem 1.22 of [Schloeder] p. 3. (Contributed by NM, 10-May-1998.) (Revised by Mario Carneiro, 30-Jan-2013.) |
⊢ ω ∈ On | ||
Theorem | dfom3 9644* | The class of natural numbers ω can be defined as the intersection of all inductive sets (which is the smallest inductive set, since inductive sets are closed under intersection), which is valid provided we assume the Axiom of Infinity. Definition 6.3 of [Eisenberg] p. 82. Definition 1.20 of [Schloeder] p. 3. (Contributed by NM, 6-Aug-1994.) |
⊢ ω = ∩ {𝑥 ∣ (∅ ∈ 𝑥 ∧ ∀𝑦 ∈ 𝑥 suc 𝑦 ∈ 𝑥)} | ||
Theorem | elom3 9645* | A simplification of elom 7860 assuming the Axiom of Infinity. (Contributed by NM, 30-May-2003.) |
⊢ (𝐴 ∈ ω ↔ ∀𝑥(Lim 𝑥 → 𝐴 ∈ 𝑥)) | ||
Theorem | dfom4 9646* | A simplification of df-om 7858 assuming the Axiom of Infinity. (Contributed by NM, 30-May-2003.) |
⊢ ω = {𝑥 ∣ ∀𝑦(Lim 𝑦 → 𝑥 ∈ 𝑦)} | ||
Theorem | dfom5 9647 | ω is the smallest limit ordinal and can be defined as such (although the Axiom of Infinity is needed to ensure that at least one limit ordinal exists). Theorem 1.23 of [Schloeder] p. 4. (Contributed by FL, 22-Feb-2011.) (Revised by Mario Carneiro, 2-Feb-2013.) |
⊢ ω = ∩ {𝑥 ∣ Lim 𝑥} | ||
Theorem | oancom 9648 | Ordinal addition is not commutative. This theorem shows a counterexample. Remark in [TakeutiZaring] p. 60. (Contributed by NM, 10-Dec-2004.) |
⊢ (1o +o ω) ≠ (ω +o 1o) | ||
Theorem | isfinite 9649 | A set is finite iff it is strictly dominated by the class of natural number. Theorem 42 of [Suppes] p. 151. The Axiom of Infinity is used for the forward implication. (Contributed by FL, 16-Apr-2011.) |
⊢ (𝐴 ∈ Fin ↔ 𝐴 ≺ ω) | ||
Theorem | fict 9650 | A finite set is countable (weaker version of isfinite 9649). (Contributed by Thierry Arnoux, 27-Mar-2018.) |
⊢ (𝐴 ∈ Fin → 𝐴 ≼ ω) | ||
Theorem | nnsdom 9651 | A natural number is strictly dominated by the set of natural numbers. Example 3 of [Enderton] p. 146. (Contributed by NM, 28-Oct-2003.) |
⊢ (𝐴 ∈ ω → 𝐴 ≺ ω) | ||
Theorem | omenps 9652 | Omega is equinumerous to a proper subset of itself. Example 13.2(4) of [Eisenberg] p. 216. (Contributed by NM, 30-Jul-2003.) |
⊢ ω ≈ (ω ∖ {∅}) | ||
Theorem | omensuc 9653 | The set of natural numbers is equinumerous to its successor. (Contributed by NM, 30-Oct-2003.) |
⊢ ω ≈ suc ω | ||
Theorem | infdifsn 9654 | Removing a singleton from an infinite set does not change the cardinality of the set. (Contributed by Mario Carneiro, 30-Apr-2015.) (Revised by Mario Carneiro, 16-May-2015.) |
⊢ (ω ≼ 𝐴 → (𝐴 ∖ {𝐵}) ≈ 𝐴) | ||
Theorem | infdiffi 9655 | Removing a finite set from an infinite set does not change the cardinality of the set. (Contributed by Mario Carneiro, 30-Apr-2015.) |
⊢ ((ω ≼ 𝐴 ∧ 𝐵 ∈ Fin) → (𝐴 ∖ 𝐵) ≈ 𝐴) | ||
Theorem | unbnn3 9656* | Any unbounded subset of natural numbers is equinumerous to the set of all natural numbers. This version of unbnn 9301 eliminates its hypothesis by assuming the Axiom of Infinity. (Contributed by NM, 4-May-2005.) |
⊢ ((𝐴 ⊆ ω ∧ ∀𝑥 ∈ ω ∃𝑦 ∈ 𝐴 𝑥 ∈ 𝑦) → 𝐴 ≈ ω) | ||
Theorem | noinfep 9657* | Using the Axiom of Regularity in the form zfregfr 9602, show that there are no infinite descending ∈-chains. Proposition 7.34 of [TakeutiZaring] p. 44. (Contributed by NM, 26-Jan-2006.) (Revised by Mario Carneiro, 22-Mar-2013.) |
⊢ ∃𝑥 ∈ ω (𝐹‘suc 𝑥) ∉ (𝐹‘𝑥) | ||
Syntax | ccnf 9658 | Extend class notation with the Cantor normal form function. |
class CNF | ||
Definition | df-cnf 9659* | Define the Cantor normal form function, which takes as input a finitely supported function from 𝑦 to 𝑥 and outputs the corresponding member of the ordinal exponential 𝑥 ↑o 𝑦. The content of the original Cantor Normal Form theorem is that for 𝑥 = ω this function is a bijection onto ω ↑o 𝑦 for any ordinal 𝑦 (or, since the function restricts naturally to different ordinals, the statement that the composite function is a bijection to On). More can be said about the function, however, and in particular it is an order isomorphism for a certain easily defined well-ordering of the finitely supported functions, which gives an alternate definition cantnffval2 9692 of this function in terms of df-oi 9507. (Contributed by Mario Carneiro, 25-May-2015.) (Revised by AV, 28-Jun-2019.) |
⊢ CNF = (𝑥 ∈ On, 𝑦 ∈ On ↦ (𝑓 ∈ {𝑔 ∈ (𝑥 ↑m 𝑦) ∣ 𝑔 finSupp ∅} ↦ ⦋OrdIso( E , (𝑓 supp ∅)) / ℎ⦌(seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (((𝑥 ↑o (ℎ‘𝑘)) ·o (𝑓‘(ℎ‘𝑘))) +o 𝑧)), ∅)‘dom ℎ))) | ||
Theorem | cantnffval 9660* | The value of the Cantor normal form function. (Contributed by Mario Carneiro, 25-May-2015.) (Revised by AV, 28-Jun-2019.) |
⊢ 𝑆 = {𝑔 ∈ (𝐴 ↑m 𝐵) ∣ 𝑔 finSupp ∅} & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) ⇒ ⊢ (𝜑 → (𝐴 CNF 𝐵) = (𝑓 ∈ 𝑆 ↦ ⦋OrdIso( E , (𝑓 supp ∅)) / ℎ⦌(seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (((𝐴 ↑o (ℎ‘𝑘)) ·o (𝑓‘(ℎ‘𝑘))) +o 𝑧)), ∅)‘dom ℎ))) | ||
Theorem | cantnfdm 9661* | The domain of the Cantor normal form function (in later lemmas we will use dom (𝐴 CNF 𝐵) to abbreviate "the set of finitely supported functions from 𝐵 to 𝐴"). (Contributed by Mario Carneiro, 25-May-2015.) (Revised by AV, 28-Jun-2019.) |
⊢ 𝑆 = {𝑔 ∈ (𝐴 ↑m 𝐵) ∣ 𝑔 finSupp ∅} & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) ⇒ ⊢ (𝜑 → dom (𝐴 CNF 𝐵) = 𝑆) | ||
Theorem | cantnfvalf 9662* | Lemma for cantnf 9690. The function appearing in cantnfval 9665 is unconditionally a function. (Contributed by Mario Carneiro, 20-May-2015.) |
⊢ 𝐹 = seqω((𝑘 ∈ 𝐴, 𝑧 ∈ 𝐵 ↦ (𝐶 +o 𝐷)), ∅) ⇒ ⊢ 𝐹:ω⟶On | ||
Theorem | cantnfs 9663 | Elementhood in the set of finitely supported functions from 𝐵 to 𝐴. (Contributed by Mario Carneiro, 25-May-2015.) (Revised by AV, 28-Jun-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) ⇒ ⊢ (𝜑 → (𝐹 ∈ 𝑆 ↔ (𝐹:𝐵⟶𝐴 ∧ 𝐹 finSupp ∅))) | ||
Theorem | cantnfcl 9664 | Basic properties of the order isomorphism 𝐺 used later. The support of an 𝐹 ∈ 𝑆 is a finite subset of 𝐴, so it is well-ordered by E and the order isomorphism has domain a finite ordinal. (Contributed by Mario Carneiro, 25-May-2015.) (Revised by AV, 28-Jun-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝐺 = OrdIso( E , (𝐹 supp ∅)) & ⊢ (𝜑 → 𝐹 ∈ 𝑆) ⇒ ⊢ (𝜑 → ( E We (𝐹 supp ∅) ∧ dom 𝐺 ∈ ω)) | ||
Theorem | cantnfval 9665* | The value of the Cantor normal form function. (Contributed by Mario Carneiro, 25-May-2015.) (Revised by AV, 28-Jun-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝐺 = OrdIso( E , (𝐹 supp ∅)) & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (((𝐴 ↑o (𝐺‘𝑘)) ·o (𝐹‘(𝐺‘𝑘))) +o 𝑧)), ∅) ⇒ ⊢ (𝜑 → ((𝐴 CNF 𝐵)‘𝐹) = (𝐻‘dom 𝐺)) | ||
Theorem | cantnfval2 9666* | Alternate expression for the value of the Cantor normal form function. (Contributed by Mario Carneiro, 25-May-2015.) (Revised by AV, 28-Jun-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝐺 = OrdIso( E , (𝐹 supp ∅)) & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (((𝐴 ↑o (𝐺‘𝑘)) ·o (𝐹‘(𝐺‘𝑘))) +o 𝑧)), ∅) ⇒ ⊢ (𝜑 → ((𝐴 CNF 𝐵)‘𝐹) = (seqω((𝑘 ∈ dom 𝐺, 𝑧 ∈ On ↦ (((𝐴 ↑o (𝐺‘𝑘)) ·o (𝐹‘(𝐺‘𝑘))) +o 𝑧)), ∅)‘dom 𝐺)) | ||
Theorem | cantnfsuc 9667* | The value of the recursive function 𝐻 at a successor. (Contributed by Mario Carneiro, 25-May-2015.) (Revised by AV, 28-Jun-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝐺 = OrdIso( E , (𝐹 supp ∅)) & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (((𝐴 ↑o (𝐺‘𝑘)) ·o (𝐹‘(𝐺‘𝑘))) +o 𝑧)), ∅) ⇒ ⊢ ((𝜑 ∧ 𝐾 ∈ ω) → (𝐻‘suc 𝐾) = (((𝐴 ↑o (𝐺‘𝐾)) ·o (𝐹‘(𝐺‘𝐾))) +o (𝐻‘𝐾))) | ||
Theorem | cantnfle 9668* | A lower bound on the CNF function. Since ((𝐴 CNF 𝐵)‘𝐹) is defined as the sum of (𝐴 ↑o 𝑥) ·o (𝐹‘𝑥) over all 𝑥 in the support of 𝐹, it is larger than any of these terms (and all other terms are zero, so we can extend the statement to all 𝐶 ∈ 𝐵 instead of just those 𝐶 in the support). (Contributed by Mario Carneiro, 28-May-2015.) (Revised by AV, 28-Jun-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝐺 = OrdIso( E , (𝐹 supp ∅)) & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (((𝐴 ↑o (𝐺‘𝑘)) ·o (𝐹‘(𝐺‘𝑘))) +o 𝑧)), ∅) & ⊢ (𝜑 → 𝐶 ∈ 𝐵) ⇒ ⊢ (𝜑 → ((𝐴 ↑o 𝐶) ·o (𝐹‘𝐶)) ⊆ ((𝐴 CNF 𝐵)‘𝐹)) | ||
Theorem | cantnflt 9669* | An upper bound on the partial sums of the CNF function. Since each term dominates all previous terms, by induction we can bound the whole sum with any exponent 𝐴 ↑o 𝐶 where 𝐶 is larger than any exponent (𝐺‘𝑥), 𝑥 ∈ 𝐾 which has been summed so far. (Contributed by Mario Carneiro, 28-May-2015.) (Revised by AV, 29-Jun-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝐺 = OrdIso( E , (𝐹 supp ∅)) & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (((𝐴 ↑o (𝐺‘𝑘)) ·o (𝐹‘(𝐺‘𝑘))) +o 𝑧)), ∅) & ⊢ (𝜑 → ∅ ∈ 𝐴) & ⊢ (𝜑 → 𝐾 ∈ suc dom 𝐺) & ⊢ (𝜑 → 𝐶 ∈ On) & ⊢ (𝜑 → (𝐺 “ 𝐾) ⊆ 𝐶) ⇒ ⊢ (𝜑 → (𝐻‘𝐾) ∈ (𝐴 ↑o 𝐶)) | ||
Theorem | cantnflt2 9670 | An upper bound on the CNF function. (Contributed by Mario Carneiro, 28-May-2015.) (Revised by AV, 29-Jun-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ (𝜑 → ∅ ∈ 𝐴) & ⊢ (𝜑 → 𝐶 ∈ On) & ⊢ (𝜑 → (𝐹 supp ∅) ⊆ 𝐶) ⇒ ⊢ (𝜑 → ((𝐴 CNF 𝐵)‘𝐹) ∈ (𝐴 ↑o 𝐶)) | ||
Theorem | cantnff 9671 | The CNF function is a function from finitely supported functions from 𝐵 to 𝐴, to the ordinal exponential 𝐴 ↑o 𝐵. (Contributed by Mario Carneiro, 28-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) ⇒ ⊢ (𝜑 → (𝐴 CNF 𝐵):𝑆⟶(𝐴 ↑o 𝐵)) | ||
Theorem | cantnf0 9672 | The value of the zero function. (Contributed by Mario Carneiro, 30-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ (𝜑 → ∅ ∈ 𝐴) ⇒ ⊢ (𝜑 → ((𝐴 CNF 𝐵)‘(𝐵 × {∅})) = ∅) | ||
Theorem | cantnfrescl 9673* | A function is finitely supported from 𝐵 to 𝐴 iff the extended function is finitely supported from 𝐷 to 𝐴. (Contributed by Mario Carneiro, 25-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ (𝜑 → 𝐷 ∈ On) & ⊢ (𝜑 → 𝐵 ⊆ 𝐷) & ⊢ ((𝜑 ∧ 𝑛 ∈ (𝐷 ∖ 𝐵)) → 𝑋 = ∅) & ⊢ (𝜑 → ∅ ∈ 𝐴) & ⊢ 𝑇 = dom (𝐴 CNF 𝐷) ⇒ ⊢ (𝜑 → ((𝑛 ∈ 𝐵 ↦ 𝑋) ∈ 𝑆 ↔ (𝑛 ∈ 𝐷 ↦ 𝑋) ∈ 𝑇)) | ||
Theorem | cantnfres 9674* | The CNF function respects extensions of the domain to a larger ordinal. (Contributed by Mario Carneiro, 25-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ (𝜑 → 𝐷 ∈ On) & ⊢ (𝜑 → 𝐵 ⊆ 𝐷) & ⊢ ((𝜑 ∧ 𝑛 ∈ (𝐷 ∖ 𝐵)) → 𝑋 = ∅) & ⊢ (𝜑 → ∅ ∈ 𝐴) & ⊢ 𝑇 = dom (𝐴 CNF 𝐷) & ⊢ (𝜑 → (𝑛 ∈ 𝐵 ↦ 𝑋) ∈ 𝑆) ⇒ ⊢ (𝜑 → ((𝐴 CNF 𝐵)‘(𝑛 ∈ 𝐵 ↦ 𝑋)) = ((𝐴 CNF 𝐷)‘(𝑛 ∈ 𝐷 ↦ 𝑋))) | ||
Theorem | cantnfp1lem1 9675* | Lemma for cantnfp1 9678. (Contributed by Mario Carneiro, 20-Jun-2015.) (Revised by AV, 30-Jun-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐴) & ⊢ (𝜑 → (𝐺 supp ∅) ⊆ 𝑋) & ⊢ 𝐹 = (𝑡 ∈ 𝐵 ↦ if(𝑡 = 𝑋, 𝑌, (𝐺‘𝑡))) ⇒ ⊢ (𝜑 → 𝐹 ∈ 𝑆) | ||
Theorem | cantnfp1lem2 9676* | Lemma for cantnfp1 9678. (Contributed by Mario Carneiro, 28-May-2015.) (Revised by AV, 30-Jun-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐴) & ⊢ (𝜑 → (𝐺 supp ∅) ⊆ 𝑋) & ⊢ 𝐹 = (𝑡 ∈ 𝐵 ↦ if(𝑡 = 𝑋, 𝑌, (𝐺‘𝑡))) & ⊢ (𝜑 → ∅ ∈ 𝑌) & ⊢ 𝑂 = OrdIso( E , (𝐹 supp ∅)) ⇒ ⊢ (𝜑 → dom 𝑂 = suc ∪ dom 𝑂) | ||
Theorem | cantnfp1lem3 9677* | Lemma for cantnfp1 9678. (Contributed by Mario Carneiro, 28-May-2015.) (Revised by AV, 1-Jul-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐴) & ⊢ (𝜑 → (𝐺 supp ∅) ⊆ 𝑋) & ⊢ 𝐹 = (𝑡 ∈ 𝐵 ↦ if(𝑡 = 𝑋, 𝑌, (𝐺‘𝑡))) & ⊢ (𝜑 → ∅ ∈ 𝑌) & ⊢ 𝑂 = OrdIso( E , (𝐹 supp ∅)) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (((𝐴 ↑o (𝑂‘𝑘)) ·o (𝐹‘(𝑂‘𝑘))) +o 𝑧)), ∅) & ⊢ 𝐾 = OrdIso( E , (𝐺 supp ∅)) & ⊢ 𝑀 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (((𝐴 ↑o (𝐾‘𝑘)) ·o (𝐺‘(𝐾‘𝑘))) +o 𝑧)), ∅) ⇒ ⊢ (𝜑 → ((𝐴 CNF 𝐵)‘𝐹) = (((𝐴 ↑o 𝑋) ·o 𝑌) +o ((𝐴 CNF 𝐵)‘𝐺))) | ||
Theorem | cantnfp1 9678* | If 𝐹 is created by adding a single term (𝐹‘𝑋) = 𝑌 to 𝐺, where 𝑋 is larger than any element of the support of 𝐺, then 𝐹 is also a finitely supported function and it is assigned the value ((𝐴 ↑o 𝑋) ·o 𝑌) +o 𝑧 where 𝑧 is the value of 𝐺. (Contributed by Mario Carneiro, 28-May-2015.) (Revised by AV, 1-Jul-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐴) & ⊢ (𝜑 → (𝐺 supp ∅) ⊆ 𝑋) & ⊢ 𝐹 = (𝑡 ∈ 𝐵 ↦ if(𝑡 = 𝑋, 𝑌, (𝐺‘𝑡))) ⇒ ⊢ (𝜑 → (𝐹 ∈ 𝑆 ∧ ((𝐴 CNF 𝐵)‘𝐹) = (((𝐴 ↑o 𝑋) ·o 𝑌) +o ((𝐴 CNF 𝐵)‘𝐺)))) | ||
Theorem | oemapso 9679* | The relation 𝑇 is a strict order on 𝑆 (a corollary of wemapso2 9550). (Contributed by Mario Carneiro, 28-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} ⇒ ⊢ (𝜑 → 𝑇 Or 𝑆) | ||
Theorem | oemapval 9680* | Value of the relation 𝑇. (Contributed by Mario Carneiro, 28-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) ⇒ ⊢ (𝜑 → (𝐹𝑇𝐺 ↔ ∃𝑧 ∈ 𝐵 ((𝐹‘𝑧) ∈ (𝐺‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝐹‘𝑤) = (𝐺‘𝑤))))) | ||
Theorem | oemapvali 9681* | If 𝐹 < 𝐺, then there is some 𝑧 witnessing this, but we can say more and in fact there is a definable expression 𝑋 that also witnesses 𝐹 < 𝐺. (Contributed by Mario Carneiro, 25-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) & ⊢ (𝜑 → 𝐹𝑇𝐺) & ⊢ 𝑋 = ∪ {𝑐 ∈ 𝐵 ∣ (𝐹‘𝑐) ∈ (𝐺‘𝑐)} ⇒ ⊢ (𝜑 → (𝑋 ∈ 𝐵 ∧ (𝐹‘𝑋) ∈ (𝐺‘𝑋) ∧ ∀𝑤 ∈ 𝐵 (𝑋 ∈ 𝑤 → (𝐹‘𝑤) = (𝐺‘𝑤)))) | ||
Theorem | cantnflem1a 9682* | Lemma for cantnf 9690. (Contributed by Mario Carneiro, 4-Jun-2015.) (Revised by AV, 2-Jul-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) & ⊢ (𝜑 → 𝐹𝑇𝐺) & ⊢ 𝑋 = ∪ {𝑐 ∈ 𝐵 ∣ (𝐹‘𝑐) ∈ (𝐺‘𝑐)} ⇒ ⊢ (𝜑 → 𝑋 ∈ (𝐺 supp ∅)) | ||
Theorem | cantnflem1b 9683* | Lemma for cantnf 9690. (Contributed by Mario Carneiro, 4-Jun-2015.) (Revised by AV, 2-Jul-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) & ⊢ (𝜑 → 𝐹𝑇𝐺) & ⊢ 𝑋 = ∪ {𝑐 ∈ 𝐵 ∣ (𝐹‘𝑐) ∈ (𝐺‘𝑐)} & ⊢ 𝑂 = OrdIso( E , (𝐺 supp ∅)) ⇒ ⊢ ((𝜑 ∧ (suc 𝑢 ∈ dom 𝑂 ∧ (◡𝑂‘𝑋) ⊆ 𝑢)) → 𝑋 ⊆ (𝑂‘𝑢)) | ||
Theorem | cantnflem1c 9684* | Lemma for cantnf 9690. (Contributed by Mario Carneiro, 4-Jun-2015.) (Revised by AV, 2-Jul-2019.) (Proof shortened by AV, 4-Apr-2020.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) & ⊢ (𝜑 → 𝐹𝑇𝐺) & ⊢ 𝑋 = ∪ {𝑐 ∈ 𝐵 ∣ (𝐹‘𝑐) ∈ (𝐺‘𝑐)} & ⊢ 𝑂 = OrdIso( E , (𝐺 supp ∅)) ⇒ ⊢ ((((𝜑 ∧ (suc 𝑢 ∈ dom 𝑂 ∧ (◡𝑂‘𝑋) ⊆ 𝑢)) ∧ 𝑥 ∈ 𝐵) ∧ ((𝐹‘𝑥) ≠ ∅ ∧ (𝑂‘𝑢) ∈ 𝑥)) → 𝑥 ∈ (𝐺 supp ∅)) | ||
Theorem | cantnflem1d 9685* | Lemma for cantnf 9690. (Contributed by Mario Carneiro, 4-Jun-2015.) (Revised by AV, 2-Jul-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) & ⊢ (𝜑 → 𝐹𝑇𝐺) & ⊢ 𝑋 = ∪ {𝑐 ∈ 𝐵 ∣ (𝐹‘𝑐) ∈ (𝐺‘𝑐)} & ⊢ 𝑂 = OrdIso( E , (𝐺 supp ∅)) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (((𝐴 ↑o (𝑂‘𝑘)) ·o (𝐺‘(𝑂‘𝑘))) +o 𝑧)), ∅) ⇒ ⊢ (𝜑 → ((𝐴 CNF 𝐵)‘(𝑥 ∈ 𝐵 ↦ if(𝑥 ⊆ 𝑋, (𝐹‘𝑥), ∅))) ∈ (𝐻‘suc (◡𝑂‘𝑋))) | ||
Theorem | cantnflem1 9686* | Lemma for cantnf 9690. This part of the proof is showing uniqueness of the Cantor normal form. We already know that the relation 𝑇 is a strict order, but we haven't shown it is a well-order yet. But being a strict order is enough to show that two distinct 𝐹, 𝐺 are 𝑇 -related as 𝐹 < 𝐺 or 𝐺 < 𝐹, and WLOG assuming that 𝐹 < 𝐺, we show that CNF respects this order and maps these two to different ordinals. (Contributed by Mario Carneiro, 28-May-2015.) (Revised by AV, 2-Jul-2019.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} & ⊢ (𝜑 → 𝐹 ∈ 𝑆) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) & ⊢ (𝜑 → 𝐹𝑇𝐺) & ⊢ 𝑋 = ∪ {𝑐 ∈ 𝐵 ∣ (𝐹‘𝑐) ∈ (𝐺‘𝑐)} & ⊢ 𝑂 = OrdIso( E , (𝐺 supp ∅)) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (((𝐴 ↑o (𝑂‘𝑘)) ·o (𝐺‘(𝑂‘𝑘))) +o 𝑧)), ∅) ⇒ ⊢ (𝜑 → ((𝐴 CNF 𝐵)‘𝐹) ∈ ((𝐴 CNF 𝐵)‘𝐺)) | ||
Theorem | cantnflem2 9687* | Lemma for cantnf 9690. (Contributed by Mario Carneiro, 28-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} & ⊢ (𝜑 → 𝐶 ∈ (𝐴 ↑o 𝐵)) & ⊢ (𝜑 → 𝐶 ⊆ ran (𝐴 CNF 𝐵)) & ⊢ (𝜑 → ∅ ∈ 𝐶) ⇒ ⊢ (𝜑 → (𝐴 ∈ (On ∖ 2o) ∧ 𝐶 ∈ (On ∖ 1o))) | ||
Theorem | cantnflem3 9688* | Lemma for cantnf 9690. Here we show existence of Cantor normal forms. Assuming (by transfinite induction) that every number less than 𝐶 has a normal form, we can use oeeu 8605 to factor 𝐶 into the form ((𝐴 ↑o 𝑋) ·o 𝑌) +o 𝑍 where 0 < 𝑌 < 𝐴 and 𝑍 < (𝐴 ↑o 𝑋) (and a fortiori 𝑋 < 𝐵). Then since 𝑍 < (𝐴 ↑o 𝑋) ≤ (𝐴 ↑o 𝑋) ·o 𝑌 ≤ 𝐶, 𝑍 has a normal form, and by appending the term (𝐴 ↑o 𝑋) ·o 𝑌 using cantnfp1 9678 we get a normal form for 𝐶. (Contributed by Mario Carneiro, 28-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} & ⊢ (𝜑 → 𝐶 ∈ (𝐴 ↑o 𝐵)) & ⊢ (𝜑 → 𝐶 ⊆ ran (𝐴 CNF 𝐵)) & ⊢ (𝜑 → ∅ ∈ 𝐶) & ⊢ 𝑋 = ∪ ∩ {𝑐 ∈ On ∣ 𝐶 ∈ (𝐴 ↑o 𝑐)} & ⊢ 𝑃 = (℩𝑑∃𝑎 ∈ On ∃𝑏 ∈ (𝐴 ↑o 𝑋)(𝑑 = ⟨𝑎, 𝑏⟩ ∧ (((𝐴 ↑o 𝑋) ·o 𝑎) +o 𝑏) = 𝐶)) & ⊢ 𝑌 = (1st ‘𝑃) & ⊢ 𝑍 = (2nd ‘𝑃) & ⊢ (𝜑 → 𝐺 ∈ 𝑆) & ⊢ (𝜑 → ((𝐴 CNF 𝐵)‘𝐺) = 𝑍) & ⊢ 𝐹 = (𝑡 ∈ 𝐵 ↦ if(𝑡 = 𝑋, 𝑌, (𝐺‘𝑡))) ⇒ ⊢ (𝜑 → 𝐶 ∈ ran (𝐴 CNF 𝐵)) | ||
Theorem | cantnflem4 9689* | Lemma for cantnf 9690. Complete the induction step of cantnflem3 9688. (Contributed by Mario Carneiro, 25-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} & ⊢ (𝜑 → 𝐶 ∈ (𝐴 ↑o 𝐵)) & ⊢ (𝜑 → 𝐶 ⊆ ran (𝐴 CNF 𝐵)) & ⊢ (𝜑 → ∅ ∈ 𝐶) & ⊢ 𝑋 = ∪ ∩ {𝑐 ∈ On ∣ 𝐶 ∈ (𝐴 ↑o 𝑐)} & ⊢ 𝑃 = (℩𝑑∃𝑎 ∈ On ∃𝑏 ∈ (𝐴 ↑o 𝑋)(𝑑 = ⟨𝑎, 𝑏⟩ ∧ (((𝐴 ↑o 𝑋) ·o 𝑎) +o 𝑏) = 𝐶)) & ⊢ 𝑌 = (1st ‘𝑃) & ⊢ 𝑍 = (2nd ‘𝑃) ⇒ ⊢ (𝜑 → 𝐶 ∈ ran (𝐴 CNF 𝐵)) | ||
Theorem | cantnf 9690* | The Cantor Normal Form theorem. The function (𝐴 CNF 𝐵), which maps a finitely supported function from 𝐵 to 𝐴 to the sum ((𝐴 ↑o 𝑓(𝑎1)) ∘ 𝑎1) +o ((𝐴 ↑o 𝑓(𝑎2)) ∘ 𝑎2) +o ... over all indices 𝑎 < 𝐵 such that 𝑓(𝑎) is nonzero, is an order isomorphism from the ordering 𝑇 of finitely supported functions to the set (𝐴 ↑o 𝐵) under the natural order. Setting 𝐴 = ω and letting 𝐵 be arbitrarily large, the surjectivity of this function implies that every ordinal has a Cantor normal form (and injectivity, together with coherence cantnfres 9674, implies that such a representation is unique). (Contributed by Mario Carneiro, 28-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} ⇒ ⊢ (𝜑 → (𝐴 CNF 𝐵) Isom 𝑇, E (𝑆, (𝐴 ↑o 𝐵))) | ||
Theorem | oemapwe 9691* | The lexicographic order on a function space of ordinals gives a well-ordering with order type equal to the ordinal exponential. This provides an alternate definition of the ordinal exponential. (Contributed by Mario Carneiro, 28-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} ⇒ ⊢ (𝜑 → (𝑇 We 𝑆 ∧ dom OrdIso(𝑇, 𝑆) = (𝐴 ↑o 𝐵))) | ||
Theorem | cantnffval2 9692* | An alternate definition of df-cnf 9659 which relies on cantnf 9690. (Note that although the use of 𝑆 seems self-referential, one can use cantnfdm 9661 to eliminate it.) (Contributed by Mario Carneiro, 28-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐵 ((𝑥‘𝑧) ∈ (𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐵 (𝑧 ∈ 𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} ⇒ ⊢ (𝜑 → (𝐴 CNF 𝐵) = ◡OrdIso(𝑇, 𝑆)) | ||
Theorem | cantnff1o 9693 | Simplify the isomorphism of cantnf 9690 to simple bijection. (Contributed by Mario Carneiro, 30-May-2015.) |
⊢ 𝑆 = dom (𝐴 CNF 𝐵) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ On) ⇒ ⊢ (𝜑 → (𝐴 CNF 𝐵):𝑆–1-1-onto→(𝐴 ↑o 𝐵)) | ||
Theorem | wemapwe 9694* | Construct lexicographic order on a function space based on a reverse well-ordering of the indices and a well-ordering of the values. (Contributed by Mario Carneiro, 29-May-2015.) (Revised by AV, 3-Jul-2019.) |
⊢ 𝑇 = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧 ∈ 𝐴 ((𝑥‘𝑧)𝑆(𝑦‘𝑧) ∧ ∀𝑤 ∈ 𝐴 (𝑧𝑅𝑤 → (𝑥‘𝑤) = (𝑦‘𝑤)))} & ⊢ 𝑈 = {𝑥 ∈ (𝐵 ↑m 𝐴) ∣ 𝑥 finSupp 𝑍} & ⊢ (𝜑 → 𝑅 We 𝐴) & ⊢ (𝜑 → 𝑆 We 𝐵) & ⊢ (𝜑 → 𝐵 ≠ ∅) & ⊢ 𝐹 = OrdIso(𝑅, 𝐴) & ⊢ 𝐺 = OrdIso(𝑆, 𝐵) & ⊢ 𝑍 = (𝐺‘∅) ⇒ ⊢ (𝜑 → 𝑇 We 𝑈) | ||
Theorem | oef1o 9695* | A bijection of the base sets induces a bijection on ordinal exponentials. (The assumption (𝐹‘∅) = ∅ can be discharged using fveqf1o 7303.) (Contributed by Mario Carneiro, 30-May-2015.) (Revised by AV, 3-Jul-2019.) |
⊢ (𝜑 → 𝐹:𝐴–1-1-onto→𝐶) & ⊢ (𝜑 → 𝐺:𝐵–1-1-onto→𝐷) & ⊢ (𝜑 → 𝐴 ∈ (On ∖ 1o)) & ⊢ (𝜑 → 𝐵 ∈ On) & ⊢ (𝜑 → 𝐶 ∈ On) & ⊢ (𝜑 → 𝐷 ∈ On) & ⊢ (𝜑 → (𝐹‘∅) = ∅) & ⊢ 𝐾 = (𝑦 ∈ {𝑥 ∈ (𝐴 ↑m 𝐵) ∣ 𝑥 finSupp ∅} ↦ (𝐹 ∘ (𝑦 ∘ ◡𝐺))) & ⊢ 𝐻 = (((𝐶 CNF 𝐷) ∘ 𝐾) ∘ ◡(𝐴 CNF 𝐵)) ⇒ ⊢ (𝜑 → 𝐻:(𝐴 ↑o 𝐵)–1-1-onto→(𝐶 ↑o 𝐷)) | ||
Theorem | cnfcomlem 9696* | Lemma for cnfcom 9697. (Contributed by Mario Carneiro, 30-May-2015.) (Revised by AV, 3-Jul-2019.) |
⊢ 𝑆 = dom (ω CNF 𝐴) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ (ω ↑o 𝐴)) & ⊢ 𝐹 = (◡(ω CNF 𝐴)‘𝐵) & ⊢ 𝐺 = OrdIso( E , (𝐹 supp ∅)) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (𝑀 +o 𝑧)), ∅) & ⊢ 𝑇 = seqω((𝑘 ∈ V, 𝑓 ∈ V ↦ 𝐾), ∅) & ⊢ 𝑀 = ((ω ↑o (𝐺‘𝑘)) ·o (𝐹‘(𝐺‘𝑘))) & ⊢ 𝐾 = ((𝑥 ∈ 𝑀 ↦ (dom 𝑓 +o 𝑥)) ∪ ◡(𝑥 ∈ dom 𝑓 ↦ (𝑀 +o 𝑥))) & ⊢ (𝜑 → 𝐼 ∈ dom 𝐺) & ⊢ (𝜑 → 𝑂 ∈ (ω ↑o (𝐺‘𝐼))) & ⊢ (𝜑 → (𝑇‘𝐼):(𝐻‘𝐼)–1-1-onto→𝑂) ⇒ ⊢ (𝜑 → (𝑇‘suc 𝐼):(𝐻‘suc 𝐼)–1-1-onto→((ω ↑o (𝐺‘𝐼)) ·o (𝐹‘(𝐺‘𝐼)))) | ||
Theorem | cnfcom 9697* | Any ordinal 𝐵 is equinumerous to the leading term of its Cantor normal form. Here we show that bijection explicitly. (Contributed by Mario Carneiro, 30-May-2015.) (Revised by AV, 3-Jul-2019.) |
⊢ 𝑆 = dom (ω CNF 𝐴) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ (ω ↑o 𝐴)) & ⊢ 𝐹 = (◡(ω CNF 𝐴)‘𝐵) & ⊢ 𝐺 = OrdIso( E , (𝐹 supp ∅)) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (𝑀 +o 𝑧)), ∅) & ⊢ 𝑇 = seqω((𝑘 ∈ V, 𝑓 ∈ V ↦ 𝐾), ∅) & ⊢ 𝑀 = ((ω ↑o (𝐺‘𝑘)) ·o (𝐹‘(𝐺‘𝑘))) & ⊢ 𝐾 = ((𝑥 ∈ 𝑀 ↦ (dom 𝑓 +o 𝑥)) ∪ ◡(𝑥 ∈ dom 𝑓 ↦ (𝑀 +o 𝑥))) & ⊢ (𝜑 → 𝐼 ∈ dom 𝐺) ⇒ ⊢ (𝜑 → (𝑇‘suc 𝐼):(𝐻‘suc 𝐼)–1-1-onto→((ω ↑o (𝐺‘𝐼)) ·o (𝐹‘(𝐺‘𝐼)))) | ||
Theorem | cnfcom2lem 9698* | Lemma for cnfcom2 9699. (Contributed by Mario Carneiro, 30-May-2015.) (Revised by AV, 3-Jul-2019.) |
⊢ 𝑆 = dom (ω CNF 𝐴) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ (ω ↑o 𝐴)) & ⊢ 𝐹 = (◡(ω CNF 𝐴)‘𝐵) & ⊢ 𝐺 = OrdIso( E , (𝐹 supp ∅)) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (𝑀 +o 𝑧)), ∅) & ⊢ 𝑇 = seqω((𝑘 ∈ V, 𝑓 ∈ V ↦ 𝐾), ∅) & ⊢ 𝑀 = ((ω ↑o (𝐺‘𝑘)) ·o (𝐹‘(𝐺‘𝑘))) & ⊢ 𝐾 = ((𝑥 ∈ 𝑀 ↦ (dom 𝑓 +o 𝑥)) ∪ ◡(𝑥 ∈ dom 𝑓 ↦ (𝑀 +o 𝑥))) & ⊢ 𝑊 = (𝐺‘∪ dom 𝐺) & ⊢ (𝜑 → ∅ ∈ 𝐵) ⇒ ⊢ (𝜑 → dom 𝐺 = suc ∪ dom 𝐺) | ||
Theorem | cnfcom2 9699* | Any nonzero ordinal 𝐵 is equinumerous to the leading term of its Cantor normal form. (Contributed by Mario Carneiro, 30-May-2015.) (Revised by AV, 3-Jul-2019.) |
⊢ 𝑆 = dom (ω CNF 𝐴) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ (ω ↑o 𝐴)) & ⊢ 𝐹 = (◡(ω CNF 𝐴)‘𝐵) & ⊢ 𝐺 = OrdIso( E , (𝐹 supp ∅)) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (𝑀 +o 𝑧)), ∅) & ⊢ 𝑇 = seqω((𝑘 ∈ V, 𝑓 ∈ V ↦ 𝐾), ∅) & ⊢ 𝑀 = ((ω ↑o (𝐺‘𝑘)) ·o (𝐹‘(𝐺‘𝑘))) & ⊢ 𝐾 = ((𝑥 ∈ 𝑀 ↦ (dom 𝑓 +o 𝑥)) ∪ ◡(𝑥 ∈ dom 𝑓 ↦ (𝑀 +o 𝑥))) & ⊢ 𝑊 = (𝐺‘∪ dom 𝐺) & ⊢ (𝜑 → ∅ ∈ 𝐵) ⇒ ⊢ (𝜑 → (𝑇‘dom 𝐺):𝐵–1-1-onto→((ω ↑o 𝑊) ·o (𝐹‘𝑊))) | ||
Theorem | cnfcom3lem 9700* | Lemma for cnfcom3 9701. (Contributed by Mario Carneiro, 30-May-2015.) (Revised by AV, 4-Jul-2019.) |
⊢ 𝑆 = dom (ω CNF 𝐴) & ⊢ (𝜑 → 𝐴 ∈ On) & ⊢ (𝜑 → 𝐵 ∈ (ω ↑o 𝐴)) & ⊢ 𝐹 = (◡(ω CNF 𝐴)‘𝐵) & ⊢ 𝐺 = OrdIso( E , (𝐹 supp ∅)) & ⊢ 𝐻 = seqω((𝑘 ∈ V, 𝑧 ∈ V ↦ (𝑀 +o 𝑧)), ∅) & ⊢ 𝑇 = seqω((𝑘 ∈ V, 𝑓 ∈ V ↦ 𝐾), ∅) & ⊢ 𝑀 = ((ω ↑o (𝐺‘𝑘)) ·o (𝐹‘(𝐺‘𝑘))) & ⊢ 𝐾 = ((𝑥 ∈ 𝑀 ↦ (dom 𝑓 +o 𝑥)) ∪ ◡(𝑥 ∈ dom 𝑓 ↦ (𝑀 +o 𝑥))) & ⊢ 𝑊 = (𝐺‘∪ dom 𝐺) & ⊢ (𝜑 → ω ⊆ 𝐵) ⇒ ⊢ (𝜑 → 𝑊 ∈ (On ∖ 1o)) |
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