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Type | Label | Description |
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Statement | ||
Definition | df-oexpi 6401* |
Define the ordinal exponentiation operation.
This definition is similar to a conventional definition of exponentiation except that it defines ∅ ↑o 𝐴 to be 1o for all 𝐴 ∈ On, in order to avoid having different cases for whether the base is ∅ or not. (Contributed by Mario Carneiro, 4-Jul-2019.) |
⊢ ↑o = (𝑥 ∈ On, 𝑦 ∈ On ↦ (rec((𝑧 ∈ V ↦ (𝑧 ·o 𝑥)), 1o)‘𝑦)) | ||
Theorem | 1on 6402 | Ordinal 1 is an ordinal number. (Contributed by NM, 29-Oct-1995.) |
⊢ 1o ∈ On | ||
Theorem | 1oex 6403 | Ordinal 1 is a set. (Contributed by BJ, 4-Jul-2022.) |
⊢ 1o ∈ V | ||
Theorem | 2on 6404 | Ordinal 2 is an ordinal number. (Contributed by NM, 18-Feb-2004.) (Proof shortened by Andrew Salmon, 12-Aug-2011.) |
⊢ 2o ∈ On | ||
Theorem | 2on0 6405 | Ordinal two is not zero. (Contributed by Scott Fenton, 17-Jun-2011.) |
⊢ 2o ≠ ∅ | ||
Theorem | 3on 6406 | Ordinal 3 is an ordinal number. (Contributed by Mario Carneiro, 5-Jan-2016.) |
⊢ 3o ∈ On | ||
Theorem | 4on 6407 | Ordinal 3 is an ordinal number. (Contributed by Mario Carneiro, 5-Jan-2016.) |
⊢ 4o ∈ On | ||
Theorem | df1o2 6408 | Expanded value of the ordinal number 1. (Contributed by NM, 4-Nov-2002.) |
⊢ 1o = {∅} | ||
Theorem | df2o3 6409 | Expanded value of the ordinal number 2. (Contributed by Mario Carneiro, 14-Aug-2015.) |
⊢ 2o = {∅, 1o} | ||
Theorem | df2o2 6410 | Expanded value of the ordinal number 2. (Contributed by NM, 29-Jan-2004.) |
⊢ 2o = {∅, {∅}} | ||
Theorem | 1n0 6411 | Ordinal one is not equal to ordinal zero. (Contributed by NM, 26-Dec-2004.) |
⊢ 1o ≠ ∅ | ||
Theorem | xp01disj 6412 | Cartesian products with the singletons of ordinals 0 and 1 are disjoint. (Contributed by NM, 2-Jun-2007.) |
⊢ ((𝐴 × {∅}) ∩ (𝐶 × {1o})) = ∅ | ||
Theorem | xp01disjl 6413 | Cartesian products with the singletons of ordinals 0 and 1 are disjoint. (Contributed by Jim Kingdon, 11-Jul-2023.) |
⊢ (({∅} × 𝐴) ∩ ({1o} × 𝐶)) = ∅ | ||
Theorem | ordgt0ge1 6414 | Two ways to express that an ordinal class is positive. (Contributed by NM, 21-Dec-2004.) |
⊢ (Ord 𝐴 → (∅ ∈ 𝐴 ↔ 1o ⊆ 𝐴)) | ||
Theorem | ordge1n0im 6415 | An ordinal greater than or equal to 1 is nonzero. (Contributed by Jim Kingdon, 26-Jun-2019.) |
⊢ (Ord 𝐴 → (1o ⊆ 𝐴 → 𝐴 ≠ ∅)) | ||
Theorem | el1o 6416 | Membership in ordinal one. (Contributed by NM, 5-Jan-2005.) |
⊢ (𝐴 ∈ 1o ↔ 𝐴 = ∅) | ||
Theorem | dif1o 6417 | Two ways to say that 𝐴 is a nonzero number of the set 𝐵. (Contributed by Mario Carneiro, 21-May-2015.) |
⊢ (𝐴 ∈ (𝐵 ∖ 1o) ↔ (𝐴 ∈ 𝐵 ∧ 𝐴 ≠ ∅)) | ||
Theorem | 2oconcl 6418 | Closure of the pair swapping function on 2o. (Contributed by Mario Carneiro, 27-Sep-2015.) |
⊢ (𝐴 ∈ 2o → (1o ∖ 𝐴) ∈ 2o) | ||
Theorem | 0lt1o 6419 | Ordinal zero is less than ordinal one. (Contributed by NM, 5-Jan-2005.) |
⊢ ∅ ∈ 1o | ||
Theorem | 0lt2o 6420 | Ordinal zero is less than ordinal two. (Contributed by Jim Kingdon, 31-Jul-2022.) |
⊢ ∅ ∈ 2o | ||
Theorem | 1lt2o 6421 | Ordinal one is less than ordinal two. (Contributed by Jim Kingdon, 31-Jul-2022.) |
⊢ 1o ∈ 2o | ||
Theorem | el2oss1o 6422 | Being an element of ordinal two implies being a subset of ordinal one. The converse is equivalent to excluded middle by ss1oel2o 14026. (Contributed by Jim Kingdon, 8-Aug-2022.) |
⊢ (𝐴 ∈ 2o → 𝐴 ⊆ 1o) | ||
Theorem | oafnex 6423 | The characteristic function for ordinal addition is defined everywhere. (Contributed by Jim Kingdon, 27-Jul-2019.) |
⊢ (𝑥 ∈ V ↦ suc 𝑥) Fn V | ||
Theorem | sucinc 6424* | Successor is increasing. (Contributed by Jim Kingdon, 25-Jun-2019.) |
⊢ 𝐹 = (𝑧 ∈ V ↦ suc 𝑧) ⇒ ⊢ ∀𝑥 𝑥 ⊆ (𝐹‘𝑥) | ||
Theorem | sucinc2 6425* | Successor is increasing. (Contributed by Jim Kingdon, 14-Jul-2019.) |
⊢ 𝐹 = (𝑧 ∈ V ↦ suc 𝑧) ⇒ ⊢ ((𝐵 ∈ On ∧ 𝐴 ∈ 𝐵) → (𝐹‘𝐴) ⊆ (𝐹‘𝐵)) | ||
Theorem | fnoa 6426 | Functionality and domain of ordinal addition. (Contributed by NM, 26-Aug-1995.) (Proof shortened by Mario Carneiro, 3-Jul-2019.) |
⊢ +o Fn (On × On) | ||
Theorem | oaexg 6427 | Ordinal addition is a set. (Contributed by Mario Carneiro, 3-Jul-2019.) |
⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → (𝐴 +o 𝐵) ∈ V) | ||
Theorem | omfnex 6428* | The characteristic function for ordinal multiplication is defined everywhere. (Contributed by Jim Kingdon, 23-Aug-2019.) |
⊢ (𝐴 ∈ 𝑉 → (𝑥 ∈ V ↦ (𝑥 +o 𝐴)) Fn V) | ||
Theorem | fnom 6429 | Functionality and domain of ordinal multiplication. (Contributed by NM, 26-Aug-1995.) (Revised by Mario Carneiro, 3-Jul-2019.) |
⊢ ·o Fn (On × On) | ||
Theorem | omexg 6430 | Ordinal multiplication is a set. (Contributed by Mario Carneiro, 3-Jul-2019.) |
⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → (𝐴 ·o 𝐵) ∈ V) | ||
Theorem | fnoei 6431 | Functionality and domain of ordinal exponentiation. (Contributed by Mario Carneiro, 29-May-2015.) (Revised by Mario Carneiro, 3-Jul-2019.) |
⊢ ↑o Fn (On × On) | ||
Theorem | oeiexg 6432 | Ordinal exponentiation is a set. (Contributed by Mario Carneiro, 3-Jul-2019.) |
⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → (𝐴 ↑o 𝐵) ∈ V) | ||
Theorem | oav 6433* | Value of ordinal addition. (Contributed by NM, 3-May-1995.) (Revised by Mario Carneiro, 8-Sep-2013.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 +o 𝐵) = (rec((𝑥 ∈ V ↦ suc 𝑥), 𝐴)‘𝐵)) | ||
Theorem | omv 6434* | Value of ordinal multiplication. (Contributed by NM, 17-Sep-1995.) (Revised by Mario Carneiro, 23-Aug-2014.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ·o 𝐵) = (rec((𝑥 ∈ V ↦ (𝑥 +o 𝐴)), ∅)‘𝐵)) | ||
Theorem | oeiv 6435* | Value of ordinal exponentiation. (Contributed by Jim Kingdon, 9-Jul-2019.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ↑o 𝐵) = (rec((𝑥 ∈ V ↦ (𝑥 ·o 𝐴)), 1o)‘𝐵)) | ||
Theorem | oa0 6436 | Addition with zero. Proposition 8.3 of [TakeutiZaring] p. 57. (Contributed by NM, 3-May-1995.) (Revised by Mario Carneiro, 8-Sep-2013.) |
⊢ (𝐴 ∈ On → (𝐴 +o ∅) = 𝐴) | ||
Theorem | om0 6437 | Ordinal multiplication with zero. Definition 8.15 of [TakeutiZaring] p. 62. (Contributed by NM, 17-Sep-1995.) (Revised by Mario Carneiro, 8-Sep-2013.) |
⊢ (𝐴 ∈ On → (𝐴 ·o ∅) = ∅) | ||
Theorem | oei0 6438 | Ordinal exponentiation with zero exponent. Definition 8.30 of [TakeutiZaring] p. 67. (Contributed by NM, 31-Dec-2004.) (Revised by Mario Carneiro, 8-Sep-2013.) |
⊢ (𝐴 ∈ On → (𝐴 ↑o ∅) = 1o) | ||
Theorem | oacl 6439 | Closure law for ordinal addition. Proposition 8.2 of [TakeutiZaring] p. 57. (Contributed by NM, 5-May-1995.) (Constructive proof by Jim Kingdon, 26-Jul-2019.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 +o 𝐵) ∈ On) | ||
Theorem | omcl 6440 | Closure law for ordinal multiplication. Proposition 8.16 of [TakeutiZaring] p. 57. (Contributed by NM, 3-Aug-2004.) (Constructive proof by Jim Kingdon, 26-Jul-2019.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ·o 𝐵) ∈ On) | ||
Theorem | oeicl 6441 | Closure law for ordinal exponentiation. (Contributed by Jim Kingdon, 26-Jul-2019.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ↑o 𝐵) ∈ On) | ||
Theorem | oav2 6442* | Value of ordinal addition. (Contributed by Mario Carneiro and Jim Kingdon, 12-Aug-2019.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 +o 𝐵) = (𝐴 ∪ ∪ 𝑥 ∈ 𝐵 suc (𝐴 +o 𝑥))) | ||
Theorem | oasuc 6443 | Addition with successor. Definition 8.1 of [TakeutiZaring] p. 56. (Contributed by NM, 3-May-1995.) (Revised by Mario Carneiro, 8-Sep-2013.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 +o suc 𝐵) = suc (𝐴 +o 𝐵)) | ||
Theorem | omv2 6444* | Value of ordinal multiplication. (Contributed by Jim Kingdon, 23-Aug-2019.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ·o 𝐵) = ∪ 𝑥 ∈ 𝐵 ((𝐴 ·o 𝑥) +o 𝐴)) | ||
Theorem | onasuc 6445 | Addition with successor. Theorem 4I(A2) of [Enderton] p. 79. (Contributed by Mario Carneiro, 16-Nov-2014.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ ω) → (𝐴 +o suc 𝐵) = suc (𝐴 +o 𝐵)) | ||
Theorem | oa1suc 6446 | Addition with 1 is same as successor. Proposition 4.34(a) of [Mendelson] p. 266. (Contributed by NM, 29-Oct-1995.) (Revised by Mario Carneiro, 16-Nov-2014.) |
⊢ (𝐴 ∈ On → (𝐴 +o 1o) = suc 𝐴) | ||
Theorem | o1p1e2 6447 | 1 + 1 = 2 for ordinal numbers. (Contributed by NM, 18-Feb-2004.) |
⊢ (1o +o 1o) = 2o | ||
Theorem | oawordi 6448 | Weak ordering property of ordinal addition. (Contributed by Jim Kingdon, 27-Jul-2019.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → (𝐴 ⊆ 𝐵 → (𝐶 +o 𝐴) ⊆ (𝐶 +o 𝐵))) | ||
Theorem | oawordriexmid 6449* | A weak ordering property of ordinal addition which implies excluded middle. The property is proposition 8.7 of [TakeutiZaring] p. 59. Compare with oawordi 6448. (Contributed by Jim Kingdon, 15-May-2022.) |
⊢ ((𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑐 ∈ On) → (𝑎 ⊆ 𝑏 → (𝑎 +o 𝑐) ⊆ (𝑏 +o 𝑐))) ⇒ ⊢ (𝜑 ∨ ¬ 𝜑) | ||
Theorem | oaword1 6450 | An ordinal is less than or equal to its sum with another. Part of Exercise 5 of [TakeutiZaring] p. 62. (Contributed by NM, 6-Dec-2004.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → 𝐴 ⊆ (𝐴 +o 𝐵)) | ||
Theorem | omsuc 6451 | Multiplication with successor. Definition 8.15 of [TakeutiZaring] p. 62. (Contributed by NM, 17-Sep-1995.) (Revised by Mario Carneiro, 8-Sep-2013.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ·o suc 𝐵) = ((𝐴 ·o 𝐵) +o 𝐴)) | ||
Theorem | onmsuc 6452 | Multiplication with successor. Theorem 4J(A2) of [Enderton] p. 80. (Contributed by NM, 20-Sep-1995.) (Revised by Mario Carneiro, 14-Nov-2014.) |
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ ω) → (𝐴 ·o suc 𝐵) = ((𝐴 ·o 𝐵) +o 𝐴)) | ||
Theorem | nna0 6453 | Addition with zero. Theorem 4I(A1) of [Enderton] p. 79. (Contributed by NM, 20-Sep-1995.) |
⊢ (𝐴 ∈ ω → (𝐴 +o ∅) = 𝐴) | ||
Theorem | nnm0 6454 | Multiplication with zero. Theorem 4J(A1) of [Enderton] p. 80. (Contributed by NM, 20-Sep-1995.) |
⊢ (𝐴 ∈ ω → (𝐴 ·o ∅) = ∅) | ||
Theorem | nnasuc 6455 | Addition with successor. Theorem 4I(A2) of [Enderton] p. 79. (Contributed by NM, 20-Sep-1995.) (Revised by Mario Carneiro, 14-Nov-2014.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 +o suc 𝐵) = suc (𝐴 +o 𝐵)) | ||
Theorem | nnmsuc 6456 | Multiplication with successor. Theorem 4J(A2) of [Enderton] p. 80. (Contributed by NM, 20-Sep-1995.) (Revised by Mario Carneiro, 14-Nov-2014.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ·o suc 𝐵) = ((𝐴 ·o 𝐵) +o 𝐴)) | ||
Theorem | nna0r 6457 | Addition to zero. Remark in proof of Theorem 4K(2) of [Enderton] p. 81. (Contributed by NM, 20-Sep-1995.) (Revised by Mario Carneiro, 14-Nov-2014.) |
⊢ (𝐴 ∈ ω → (∅ +o 𝐴) = 𝐴) | ||
Theorem | nnm0r 6458 | Multiplication with zero. Exercise 16 of [Enderton] p. 82. (Contributed by NM, 20-Sep-1995.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ (𝐴 ∈ ω → (∅ ·o 𝐴) = ∅) | ||
Theorem | nnacl 6459 | Closure of addition of natural numbers. Proposition 8.9 of [TakeutiZaring] p. 59. (Contributed by NM, 20-Sep-1995.) (Proof shortened by Andrew Salmon, 22-Oct-2011.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 +o 𝐵) ∈ ω) | ||
Theorem | nnmcl 6460 | Closure of multiplication of natural numbers. Proposition 8.17 of [TakeutiZaring] p. 63. (Contributed by NM, 20-Sep-1995.) (Proof shortened by Andrew Salmon, 22-Oct-2011.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ·o 𝐵) ∈ ω) | ||
Theorem | nnacli 6461 | ω is closed under addition. Inference form of nnacl 6459. (Contributed by Scott Fenton, 20-Apr-2012.) |
⊢ 𝐴 ∈ ω & ⊢ 𝐵 ∈ ω ⇒ ⊢ (𝐴 +o 𝐵) ∈ ω | ||
Theorem | nnmcli 6462 | ω is closed under multiplication. Inference form of nnmcl 6460. (Contributed by Scott Fenton, 20-Apr-2012.) |
⊢ 𝐴 ∈ ω & ⊢ 𝐵 ∈ ω ⇒ ⊢ (𝐴 ·o 𝐵) ∈ ω | ||
Theorem | nnacom 6463 | Addition of natural numbers is commutative. Theorem 4K(2) of [Enderton] p. 81. (Contributed by NM, 6-May-1995.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 +o 𝐵) = (𝐵 +o 𝐴)) | ||
Theorem | nnaass 6464 | Addition of natural numbers is associative. Theorem 4K(1) of [Enderton] p. 81. (Contributed by NM, 20-Sep-1995.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) → ((𝐴 +o 𝐵) +o 𝐶) = (𝐴 +o (𝐵 +o 𝐶))) | ||
Theorem | nndi 6465 | Distributive law for natural numbers (left-distributivity). Theorem 4K(3) of [Enderton] p. 81. (Contributed by NM, 20-Sep-1995.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) → (𝐴 ·o (𝐵 +o 𝐶)) = ((𝐴 ·o 𝐵) +o (𝐴 ·o 𝐶))) | ||
Theorem | nnmass 6466 | Multiplication of natural numbers is associative. Theorem 4K(4) of [Enderton] p. 81. (Contributed by NM, 20-Sep-1995.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) → ((𝐴 ·o 𝐵) ·o 𝐶) = (𝐴 ·o (𝐵 ·o 𝐶))) | ||
Theorem | nnmsucr 6467 | Multiplication with successor. Exercise 16 of [Enderton] p. 82. (Contributed by NM, 21-Sep-1995.) (Proof shortened by Andrew Salmon, 22-Oct-2011.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (suc 𝐴 ·o 𝐵) = ((𝐴 ·o 𝐵) +o 𝐵)) | ||
Theorem | nnmcom 6468 | Multiplication of natural numbers is commutative. Theorem 4K(5) of [Enderton] p. 81. (Contributed by NM, 21-Sep-1995.) (Proof shortened by Andrew Salmon, 22-Oct-2011.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ·o 𝐵) = (𝐵 ·o 𝐴)) | ||
Theorem | nndir 6469 | Distributive law for natural numbers (right-distributivity). (Contributed by Jim Kingdon, 3-Dec-2019.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) → ((𝐴 +o 𝐵) ·o 𝐶) = ((𝐴 ·o 𝐶) +o (𝐵 ·o 𝐶))) | ||
Theorem | nnsucelsuc 6470 | Membership is inherited by successors. The reverse direction holds for all ordinals, as seen at onsucelsucr 4492, but the forward direction, for all ordinals, implies excluded middle as seen as onsucelsucexmid 4514. (Contributed by Jim Kingdon, 25-Aug-2019.) |
⊢ (𝐵 ∈ ω → (𝐴 ∈ 𝐵 ↔ suc 𝐴 ∈ suc 𝐵)) | ||
Theorem | nnsucsssuc 6471 | Membership is inherited by successors. The reverse direction holds for all ordinals, as seen at onsucsssucr 4493, but the forward direction, for all ordinals, implies excluded middle as seen as onsucsssucexmid 4511. (Contributed by Jim Kingdon, 25-Aug-2019.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 ↔ suc 𝐴 ⊆ suc 𝐵)) | ||
Theorem | nntri3or 6472 | Trichotomy for natural numbers. (Contributed by Jim Kingdon, 25-Aug-2019.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴)) | ||
Theorem | nntri2 6473 | A trichotomy law for natural numbers. (Contributed by Jim Kingdon, 28-Aug-2019.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ∈ 𝐵 ↔ ¬ (𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴))) | ||
Theorem | nnsucuniel 6474 | Given an element 𝐴 of the union of a natural number 𝐵, suc 𝐴 is an element of 𝐵 itself. The reverse direction holds for all ordinals (sucunielr 4494). The forward direction for all ordinals implies excluded middle (ordsucunielexmid 4515). (Contributed by Jim Kingdon, 13-Mar-2022.) |
⊢ (𝐵 ∈ ω → (𝐴 ∈ ∪ 𝐵 ↔ suc 𝐴 ∈ 𝐵)) | ||
Theorem | nntri1 6475 | A trichotomy law for natural numbers. (Contributed by Jim Kingdon, 28-Aug-2019.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 ↔ ¬ 𝐵 ∈ 𝐴)) | ||
Theorem | nntri3 6476 | A trichotomy law for natural numbers. (Contributed by Jim Kingdon, 15-May-2020.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 = 𝐵 ↔ (¬ 𝐴 ∈ 𝐵 ∧ ¬ 𝐵 ∈ 𝐴))) | ||
Theorem | nntri2or2 6477 | A trichotomy law for natural numbers. (Contributed by Jim Kingdon, 15-Sep-2021.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 ∨ 𝐵 ⊆ 𝐴)) | ||
Theorem | nndceq 6478 | Equality of natural numbers is decidable. Theorem 7.2.6 of [HoTT], p. (varies). For the specific case where 𝐵 is zero, see nndceq0 4602. (Contributed by Jim Kingdon, 31-Aug-2019.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → DECID 𝐴 = 𝐵) | ||
Theorem | nndcel 6479 | Set membership between two natural numbers is decidable. (Contributed by Jim Kingdon, 6-Sep-2019.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → DECID 𝐴 ∈ 𝐵) | ||
Theorem | nnsseleq 6480 | For natural numbers, inclusion is equivalent to membership or equality. (Contributed by Jim Kingdon, 16-Sep-2021.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 ↔ (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵))) | ||
Theorem | nnsssuc 6481 | A natural number is a subset of another natural number if and only if it belongs to its successor. (Contributed by Jim Kingdon, 22-Jul-2023.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 ↔ 𝐴 ∈ suc 𝐵)) | ||
Theorem | nntr2 6482 | Transitive law for natural numbers. (Contributed by Jim Kingdon, 22-Jul-2023.) |
⊢ ((𝐴 ∈ ω ∧ 𝐶 ∈ ω) → ((𝐴 ⊆ 𝐵 ∧ 𝐵 ∈ 𝐶) → 𝐴 ∈ 𝐶)) | ||
Theorem | dcdifsnid 6483* | If we remove a single element from a set with decidable equality then put it back in, we end up with the original set. This strengthens difsnss 3726 from subset to equality but the proof relies on equality being decidable. (Contributed by Jim Kingdon, 17-Jun-2022.) |
⊢ ((∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 DECID 𝑥 = 𝑦 ∧ 𝐵 ∈ 𝐴) → ((𝐴 ∖ {𝐵}) ∪ {𝐵}) = 𝐴) | ||
Theorem | fnsnsplitdc 6484* | Split a function into a single point and all the rest. (Contributed by Stefan O'Rear, 27-Feb-2015.) (Revised by Jim Kingdon, 29-Jan-2023.) |
⊢ ((∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 DECID 𝑥 = 𝑦 ∧ 𝐹 Fn 𝐴 ∧ 𝑋 ∈ 𝐴) → 𝐹 = ((𝐹 ↾ (𝐴 ∖ {𝑋})) ∪ {〈𝑋, (𝐹‘𝑋)〉})) | ||
Theorem | funresdfunsndc 6485* | Restricting a function to a domain without one element of the domain of the function, and adding a pair of this element and the function value of the element results in the function itself, where equality is decidable. (Contributed by AV, 2-Dec-2018.) (Revised by Jim Kingdon, 30-Jan-2023.) |
⊢ ((∀𝑥 ∈ dom 𝐹∀𝑦 ∈ dom 𝐹DECID 𝑥 = 𝑦 ∧ Fun 𝐹 ∧ 𝑋 ∈ dom 𝐹) → ((𝐹 ↾ (V ∖ {𝑋})) ∪ {〈𝑋, (𝐹‘𝑋)〉}) = 𝐹) | ||
Theorem | nndifsnid 6486 | If we remove a single element from a natural number then put it back in, we end up with the original natural number. This strengthens difsnss 3726 from subset to equality but the proof relies on equality being decidable. (Contributed by Jim Kingdon, 31-Aug-2021.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ 𝐴) → ((𝐴 ∖ {𝐵}) ∪ {𝐵}) = 𝐴) | ||
Theorem | nnaordi 6487 | Ordering property of addition. Proposition 8.4 of [TakeutiZaring] p. 58, limited to natural numbers. (Contributed by NM, 3-Feb-1996.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ ((𝐵 ∈ ω ∧ 𝐶 ∈ ω) → (𝐴 ∈ 𝐵 → (𝐶 +o 𝐴) ∈ (𝐶 +o 𝐵))) | ||
Theorem | nnaord 6488 | Ordering property of addition. Proposition 8.4 of [TakeutiZaring] p. 58, limited to natural numbers, and its converse. (Contributed by NM, 7-Mar-1996.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) → (𝐴 ∈ 𝐵 ↔ (𝐶 +o 𝐴) ∈ (𝐶 +o 𝐵))) | ||
Theorem | nnaordr 6489 | Ordering property of addition of natural numbers. (Contributed by NM, 9-Nov-2002.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) → (𝐴 ∈ 𝐵 ↔ (𝐴 +o 𝐶) ∈ (𝐵 +o 𝐶))) | ||
Theorem | nnaword 6490 | Weak ordering property of addition. (Contributed by NM, 17-Sep-1995.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) → (𝐴 ⊆ 𝐵 ↔ (𝐶 +o 𝐴) ⊆ (𝐶 +o 𝐵))) | ||
Theorem | nnacan 6491 | Cancellation law for addition of natural numbers. (Contributed by NM, 27-Oct-1995.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) → ((𝐴 +o 𝐵) = (𝐴 +o 𝐶) ↔ 𝐵 = 𝐶)) | ||
Theorem | nnaword1 6492 | Weak ordering property of addition. (Contributed by NM, 9-Nov-2002.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → 𝐴 ⊆ (𝐴 +o 𝐵)) | ||
Theorem | nnaword2 6493 | Weak ordering property of addition. (Contributed by NM, 9-Nov-2002.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → 𝐴 ⊆ (𝐵 +o 𝐴)) | ||
Theorem | nnawordi 6494 | Adding to both sides of an inequality in ω. (Contributed by Scott Fenton, 16-Apr-2012.) (Revised by Mario Carneiro, 12-May-2012.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) → (𝐴 ⊆ 𝐵 → (𝐴 +o 𝐶) ⊆ (𝐵 +o 𝐶))) | ||
Theorem | nnmordi 6495 | Ordering property of multiplication. Half of Proposition 8.19 of [TakeutiZaring] p. 63, limited to natural numbers. (Contributed by NM, 18-Sep-1995.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ (((𝐵 ∈ ω ∧ 𝐶 ∈ ω) ∧ ∅ ∈ 𝐶) → (𝐴 ∈ 𝐵 → (𝐶 ·o 𝐴) ∈ (𝐶 ·o 𝐵))) | ||
Theorem | nnmord 6496 | Ordering property of multiplication. Proposition 8.19 of [TakeutiZaring] p. 63, limited to natural numbers. (Contributed by NM, 22-Jan-1996.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) → ((𝐴 ∈ 𝐵 ∧ ∅ ∈ 𝐶) ↔ (𝐶 ·o 𝐴) ∈ (𝐶 ·o 𝐵))) | ||
Theorem | nnmword 6497 | Weak ordering property of ordinal multiplication. (Contributed by Mario Carneiro, 17-Nov-2014.) |
⊢ (((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) ∧ ∅ ∈ 𝐶) → (𝐴 ⊆ 𝐵 ↔ (𝐶 ·o 𝐴) ⊆ (𝐶 ·o 𝐵))) | ||
Theorem | nnmcan 6498 | Cancellation law for multiplication of natural numbers. (Contributed by NM, 26-Oct-1995.) (Revised by Mario Carneiro, 15-Nov-2014.) |
⊢ (((𝐴 ∈ ω ∧ 𝐵 ∈ ω ∧ 𝐶 ∈ ω) ∧ ∅ ∈ 𝐴) → ((𝐴 ·o 𝐵) = (𝐴 ·o 𝐶) ↔ 𝐵 = 𝐶)) | ||
Theorem | 1onn 6499 | One is a natural number. (Contributed by NM, 29-Oct-1995.) |
⊢ 1o ∈ ω | ||
Theorem | 2onn 6500 | The ordinal 2 is a natural number. (Contributed by NM, 28-Sep-2004.) |
⊢ 2o ∈ ω |
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