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| Type | Label | Description |
|---|---|---|
| Statement | ||
| Theorem | lt2halves 12501 | A sum is less than the whole if each term is less than half. (Contributed by NM, 13-Dec-2006.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → ((𝐴 < (𝐶 / 2) ∧ 𝐵 < (𝐶 / 2)) → (𝐴 + 𝐵) < 𝐶)) | ||
| Theorem | addltmul 12502 | Sum is less than product for numbers greater than 2. (Contributed by Stefan Allan, 24-Sep-2010.) |
| ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (2 < 𝐴 ∧ 2 < 𝐵)) → (𝐴 + 𝐵) < (𝐴 · 𝐵)) | ||
| Theorem | nominpos 12503* | There is no smallest positive real number. (Contributed by NM, 28-Oct-2004.) |
| ⊢ ¬ ∃𝑥 ∈ ℝ (0 < 𝑥 ∧ ¬ ∃𝑦 ∈ ℝ (0 < 𝑦 ∧ 𝑦 < 𝑥)) | ||
| Theorem | avglt1 12504 | Ordering property for average. (Contributed by Mario Carneiro, 28-May-2014.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 < 𝐵 ↔ 𝐴 < ((𝐴 + 𝐵) / 2))) | ||
| Theorem | avglt2 12505 | Ordering property for average. (Contributed by Mario Carneiro, 28-May-2014.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 < 𝐵 ↔ ((𝐴 + 𝐵) / 2) < 𝐵)) | ||
| Theorem | avgle1 12506 | Ordering property for average. (Contributed by Mario Carneiro, 28-May-2014.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 ≤ 𝐵 ↔ 𝐴 ≤ ((𝐴 + 𝐵) / 2))) | ||
| Theorem | avgle2 12507 | Ordering property for average. (Contributed by Jeff Hankins, 15-Sep-2013.) (Revised by Mario Carneiro, 28-May-2014.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 ≤ 𝐵 ↔ ((𝐴 + 𝐵) / 2) ≤ 𝐵)) | ||
| Theorem | avgle 12508 | The average of two numbers is less than or equal to at least one of them. (Contributed by NM, 9-Dec-2005.) (Revised by Mario Carneiro, 28-May-2014.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (((𝐴 + 𝐵) / 2) ≤ 𝐴 ∨ ((𝐴 + 𝐵) / 2) ≤ 𝐵)) | ||
| Theorem | 2timesd 12509 | Two times a number. (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (2 · 𝐴) = (𝐴 + 𝐴)) | ||
| Theorem | times2d 12510 | A number times 2. (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (𝐴 · 2) = (𝐴 + 𝐴)) | ||
| Theorem | halfcld 12511 | Closure of half of a number (frequently used special case). (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (𝐴 / 2) ∈ ℂ) | ||
| Theorem | 2halvesd 12512 | Two halves make a whole. (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → ((𝐴 / 2) + (𝐴 / 2)) = 𝐴) | ||
| Theorem | rehalfcld 12513 | Real closure of half. (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℝ) ⇒ ⊢ (𝜑 → (𝐴 / 2) ∈ ℝ) | ||
| Theorem | lt2halvesd 12514 | A sum is less than the whole if each term is less than half. (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → 𝐴 < (𝐶 / 2)) & ⊢ (𝜑 → 𝐵 < (𝐶 / 2)) ⇒ ⊢ (𝜑 → (𝐴 + 𝐵) < 𝐶) | ||
| Theorem | rehalfcli 12515 | Half a real number is real. Inference form. (Contributed by David Moews, 28-Feb-2017.) |
| ⊢ 𝐴 ∈ ℝ ⇒ ⊢ (𝐴 / 2) ∈ ℝ | ||
| Theorem | lt2addmuld 12516 | If two real numbers are less than a third real number, the sum of the two real numbers is less than twice the third real number. (Contributed by Glauco Siliprandi, 11-Dec-2019.) |
| ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → 𝐴 < 𝐶) & ⊢ (𝜑 → 𝐵 < 𝐶) ⇒ ⊢ (𝜑 → (𝐴 + 𝐵) < (2 · 𝐶)) | ||
| Theorem | add1p1 12517 | Adding two times 1 to a number. (Contributed by AV, 22-Sep-2018.) |
| ⊢ (𝑁 ∈ ℂ → ((𝑁 + 1) + 1) = (𝑁 + 2)) | ||
| Theorem | sub1m1 12518 | Subtracting two times 1 from a number. (Contributed by AV, 23-Oct-2018.) |
| ⊢ (𝑁 ∈ ℂ → ((𝑁 − 1) − 1) = (𝑁 − 2)) | ||
| Theorem | cnm2m1cnm3 12519 | Subtracting 2 and afterwards 1 from a number results in the difference between the number and 3. (Contributed by Alexander van der Vekens, 16-Sep-2018.) |
| ⊢ (𝐴 ∈ ℂ → ((𝐴 − 2) − 1) = (𝐴 − 3)) | ||
| Theorem | xp1d2m1eqxm1d2 12520 | A complex number increased by 1, then divided by 2, then decreased by 1 equals the complex number decreased by 1 and then divided by 2. (Contributed by AV, 24-May-2020.) |
| ⊢ (𝑋 ∈ ℂ → (((𝑋 + 1) / 2) − 1) = ((𝑋 − 1) / 2)) | ||
| Theorem | div4p1lem1div2 12521 | An integer greater than 5, divided by 4 and increased by 1, is less than or equal to the half of the integer minus 1. (Contributed by AV, 8-Jul-2021.) |
| ⊢ ((𝑁 ∈ ℝ ∧ 6 ≤ 𝑁) → ((𝑁 / 4) + 1) ≤ ((𝑁 − 1) / 2)) | ||
| Theorem | nnunb 12522* | The set of positive integers is unbounded above. Theorem I.28 of [Apostol] p. 26. (Contributed by NM, 21-Jan-1997.) |
| ⊢ ¬ ∃𝑥 ∈ ℝ ∀𝑦 ∈ ℕ (𝑦 < 𝑥 ∨ 𝑦 = 𝑥) | ||
| Theorem | arch 12523* | Archimedean property of real numbers. For any real number, there is an integer greater than it. Theorem I.29 of [Apostol] p. 26. (Contributed by NM, 21-Jan-1997.) |
| ⊢ (𝐴 ∈ ℝ → ∃𝑛 ∈ ℕ 𝐴 < 𝑛) | ||
| Theorem | nnrecl 12524* | There exists a positive integer whose reciprocal is less than a given positive real. Exercise 3 of [Apostol] p. 28. (Contributed by NM, 8-Nov-2004.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 0 < 𝐴) → ∃𝑛 ∈ ℕ (1 / 𝑛) < 𝐴) | ||
| Theorem | bndndx 12525* | A bounded real sequence 𝐴(𝑘) is less than or equal to at least one of its indices. (Contributed by NM, 18-Jan-2008.) |
| ⊢ (∃𝑥 ∈ ℝ ∀𝑘 ∈ ℕ (𝐴 ∈ ℝ ∧ 𝐴 ≤ 𝑥) → ∃𝑘 ∈ ℕ 𝐴 ≤ 𝑘) | ||
| Syntax | cn0 12526 | Extend class notation to include the class of nonnegative integers. |
| class ℕ0 | ||
| Definition | df-n0 12527 | Define the set of nonnegative integers. (Contributed by Raph Levien, 10-Dec-2002.) |
| ⊢ ℕ0 = (ℕ ∪ {0}) | ||
| Theorem | elnn0 12528 | Nonnegative integers expressed in terms of naturals and zero. (Contributed by Raph Levien, 10-Dec-2002.) |
| ⊢ (𝐴 ∈ ℕ0 ↔ (𝐴 ∈ ℕ ∨ 𝐴 = 0)) | ||
| Theorem | nnssnn0 12529 | Positive naturals are a subset of nonnegative integers. (Contributed by Raph Levien, 10-Dec-2002.) |
| ⊢ ℕ ⊆ ℕ0 | ||
| Theorem | nn0ssre 12530 | Nonnegative integers are a subset of the reals. (Contributed by Raph Levien, 10-Dec-2002.) |
| ⊢ ℕ0 ⊆ ℝ | ||
| Theorem | nn0sscn 12531 | Nonnegative integers are a subset of the complex numbers. (Contributed by NM, 9-May-2004.) Reduce dependencies on axioms. (Revised by Steven Nguyen, 8-Oct-2022.) |
| ⊢ ℕ0 ⊆ ℂ | ||
| Theorem | nn0ex 12532 | The set of nonnegative integers exists. (Contributed by NM, 18-Jul-2004.) |
| ⊢ ℕ0 ∈ V | ||
| Theorem | nnnn0 12533 | A positive integer is a nonnegative integer. (Contributed by NM, 9-May-2004.) |
| ⊢ (𝐴 ∈ ℕ → 𝐴 ∈ ℕ0) | ||
| Theorem | nnnn0i 12534 | A positive integer is a nonnegative integer. (Contributed by NM, 20-Jun-2005.) |
| ⊢ 𝑁 ∈ ℕ ⇒ ⊢ 𝑁 ∈ ℕ0 | ||
| Theorem | nn0re 12535 | A nonnegative integer is a real number. (Contributed by NM, 9-May-2004.) |
| ⊢ (𝐴 ∈ ℕ0 → 𝐴 ∈ ℝ) | ||
| Theorem | nn0cn 12536 | A nonnegative integer is a complex number. (Contributed by NM, 9-May-2004.) |
| ⊢ (𝐴 ∈ ℕ0 → 𝐴 ∈ ℂ) | ||
| Theorem | nn0rei 12537 | A nonnegative integer is a real number. (Contributed by NM, 14-May-2003.) |
| ⊢ 𝐴 ∈ ℕ0 ⇒ ⊢ 𝐴 ∈ ℝ | ||
| Theorem | nn0cni 12538 | A nonnegative integer is a complex number. (Contributed by NM, 14-May-2003.) Reduce dependencies on axioms. (Revised by Steven Nguyen, 8-Oct-2022.) |
| ⊢ 𝐴 ∈ ℕ0 ⇒ ⊢ 𝐴 ∈ ℂ | ||
| Theorem | dfn2 12539 | The set of positive integers defined in terms of nonnegative integers. (Contributed by NM, 23-Sep-2007.) (Proof shortened by Mario Carneiro, 13-Feb-2013.) |
| ⊢ ℕ = (ℕ0 ∖ {0}) | ||
| Theorem | elnnne0 12540 | The positive integer property expressed in terms of difference from zero. (Contributed by Stefan O'Rear, 12-Sep-2015.) |
| ⊢ (𝑁 ∈ ℕ ↔ (𝑁 ∈ ℕ0 ∧ 𝑁 ≠ 0)) | ||
| Theorem | 0nn0 12541 | 0 is a nonnegative integer. (Contributed by Raph Levien, 10-Dec-2002.) |
| ⊢ 0 ∈ ℕ0 | ||
| Theorem | 1nn0 12542 | 1 is a nonnegative integer. (Contributed by Raph Levien, 10-Dec-2002.) |
| ⊢ 1 ∈ ℕ0 | ||
| Theorem | 2nn0 12543 | 2 is a nonnegative integer. (Contributed by Raph Levien, 10-Dec-2002.) |
| ⊢ 2 ∈ ℕ0 | ||
| Theorem | 3nn0 12544 | 3 is a nonnegative integer. (Contributed by Mario Carneiro, 18-Feb-2014.) |
| ⊢ 3 ∈ ℕ0 | ||
| Theorem | 4nn0 12545 | 4 is a nonnegative integer. (Contributed by Mario Carneiro, 18-Feb-2014.) |
| ⊢ 4 ∈ ℕ0 | ||
| Theorem | 5nn0 12546 | 5 is a nonnegative integer. (Contributed by Mario Carneiro, 19-Apr-2015.) |
| ⊢ 5 ∈ ℕ0 | ||
| Theorem | 6nn0 12547 | 6 is a nonnegative integer. (Contributed by Mario Carneiro, 19-Apr-2015.) |
| ⊢ 6 ∈ ℕ0 | ||
| Theorem | 7nn0 12548 | 7 is a nonnegative integer. (Contributed by Mario Carneiro, 19-Apr-2015.) |
| ⊢ 7 ∈ ℕ0 | ||
| Theorem | 8nn0 12549 | 8 is a nonnegative integer. (Contributed by Mario Carneiro, 19-Apr-2015.) |
| ⊢ 8 ∈ ℕ0 | ||
| Theorem | 9nn0 12550 | 9 is a nonnegative integer. (Contributed by Mario Carneiro, 19-Apr-2015.) |
| ⊢ 9 ∈ ℕ0 | ||
| Theorem | nn0ge0 12551 | A nonnegative integer is greater than or equal to zero. (Contributed by NM, 9-May-2004.) (Revised by Mario Carneiro, 16-May-2014.) |
| ⊢ (𝑁 ∈ ℕ0 → 0 ≤ 𝑁) | ||
| Theorem | nn0nlt0 12552 | A nonnegative integer is not less than zero. (Contributed by NM, 9-May-2004.) (Revised by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝐴 ∈ ℕ0 → ¬ 𝐴 < 0) | ||
| Theorem | nn0ge0i 12553 | Nonnegative integers are nonnegative. (Contributed by Raph Levien, 10-Dec-2002.) |
| ⊢ 𝑁 ∈ ℕ0 ⇒ ⊢ 0 ≤ 𝑁 | ||
| Theorem | nn0le0eq0 12554 | A nonnegative integer is less than or equal to zero iff it is equal to zero. (Contributed by NM, 9-Dec-2005.) |
| ⊢ (𝑁 ∈ ℕ0 → (𝑁 ≤ 0 ↔ 𝑁 = 0)) | ||
| Theorem | nn0p1gt0 12555 | A nonnegative integer increased by 1 is greater than 0. (Contributed by Alexander van der Vekens, 3-Oct-2018.) |
| ⊢ (𝑁 ∈ ℕ0 → 0 < (𝑁 + 1)) | ||
| Theorem | nnnn0addcl 12556 | A positive integer plus a nonnegative integer is a positive integer. (Contributed by NM, 20-Apr-2005.) (Proof shortened by Mario Carneiro, 16-May-2014.) |
| ⊢ ((𝑀 ∈ ℕ ∧ 𝑁 ∈ ℕ0) → (𝑀 + 𝑁) ∈ ℕ) | ||
| Theorem | nn0nnaddcl 12557 | A nonnegative integer plus a positive integer is a positive integer. (Contributed by NM, 22-Dec-2005.) |
| ⊢ ((𝑀 ∈ ℕ0 ∧ 𝑁 ∈ ℕ) → (𝑀 + 𝑁) ∈ ℕ) | ||
| Theorem | 0mnnnnn0 12558 | The result of subtracting a positive integer from 0 is not a nonnegative integer. (Contributed by Alexander van der Vekens, 19-Mar-2018.) |
| ⊢ (𝑁 ∈ ℕ → (0 − 𝑁) ∉ ℕ0) | ||
| Theorem | un0addcl 12559 | If 𝑆 is closed under addition, then so is 𝑆 ∪ {0}. (Contributed by Mario Carneiro, 17-Jul-2014.) |
| ⊢ (𝜑 → 𝑆 ⊆ ℂ) & ⊢ 𝑇 = (𝑆 ∪ {0}) & ⊢ ((𝜑 ∧ (𝑀 ∈ 𝑆 ∧ 𝑁 ∈ 𝑆)) → (𝑀 + 𝑁) ∈ 𝑆) ⇒ ⊢ ((𝜑 ∧ (𝑀 ∈ 𝑇 ∧ 𝑁 ∈ 𝑇)) → (𝑀 + 𝑁) ∈ 𝑇) | ||
| Theorem | un0mulcl 12560 | If 𝑆 is closed under multiplication, then so is 𝑆 ∪ {0}. (Contributed by Mario Carneiro, 17-Jul-2014.) |
| ⊢ (𝜑 → 𝑆 ⊆ ℂ) & ⊢ 𝑇 = (𝑆 ∪ {0}) & ⊢ ((𝜑 ∧ (𝑀 ∈ 𝑆 ∧ 𝑁 ∈ 𝑆)) → (𝑀 · 𝑁) ∈ 𝑆) ⇒ ⊢ ((𝜑 ∧ (𝑀 ∈ 𝑇 ∧ 𝑁 ∈ 𝑇)) → (𝑀 · 𝑁) ∈ 𝑇) | ||
| Theorem | nn0addcl 12561 | Closure of addition of nonnegative integers. (Contributed by Raph Levien, 10-Dec-2002.) (Proof shortened by Mario Carneiro, 17-Jul-2014.) |
| ⊢ ((𝑀 ∈ ℕ0 ∧ 𝑁 ∈ ℕ0) → (𝑀 + 𝑁) ∈ ℕ0) | ||
| Theorem | nn0mulcl 12562 | Closure of multiplication of nonnegative integers. (Contributed by NM, 22-Jul-2004.) (Proof shortened by Mario Carneiro, 17-Jul-2014.) |
| ⊢ ((𝑀 ∈ ℕ0 ∧ 𝑁 ∈ ℕ0) → (𝑀 · 𝑁) ∈ ℕ0) | ||
| Theorem | nn0addcli 12563 | Closure of addition of nonnegative integers, inference form. (Contributed by Raph Levien, 10-Dec-2002.) |
| ⊢ 𝑀 ∈ ℕ0 & ⊢ 𝑁 ∈ ℕ0 ⇒ ⊢ (𝑀 + 𝑁) ∈ ℕ0 | ||
| Theorem | nn0mulcli 12564 | Closure of multiplication of nonnegative integers, inference form. (Contributed by Raph Levien, 10-Dec-2002.) |
| ⊢ 𝑀 ∈ ℕ0 & ⊢ 𝑁 ∈ ℕ0 ⇒ ⊢ (𝑀 · 𝑁) ∈ ℕ0 | ||
| Theorem | nn0p1nn 12565 | A nonnegative integer plus 1 is a positive integer. Strengthening of peano2nn 12278. (Contributed by Raph Levien, 30-Jun-2006.) (Revised by Mario Carneiro, 16-May-2014.) |
| ⊢ (𝑁 ∈ ℕ0 → (𝑁 + 1) ∈ ℕ) | ||
| Theorem | peano2nn0 12566 | Second Peano postulate for nonnegative integers. (Contributed by NM, 9-May-2004.) |
| ⊢ (𝑁 ∈ ℕ0 → (𝑁 + 1) ∈ ℕ0) | ||
| Theorem | nnm1nn0 12567 | A positive integer minus 1 is a nonnegative integer. (Contributed by Jason Orendorff, 24-Jan-2007.) (Revised by Mario Carneiro, 16-May-2014.) |
| ⊢ (𝑁 ∈ ℕ → (𝑁 − 1) ∈ ℕ0) | ||
| Theorem | elnn0nn 12568 | The nonnegative integer property expressed in terms of positive integers. (Contributed by NM, 10-May-2004.) (Proof shortened by Mario Carneiro, 16-May-2014.) |
| ⊢ (𝑁 ∈ ℕ0 ↔ (𝑁 ∈ ℂ ∧ (𝑁 + 1) ∈ ℕ)) | ||
| Theorem | elnnnn0 12569 | The positive integer property expressed in terms of nonnegative integers. (Contributed by NM, 10-May-2004.) |
| ⊢ (𝑁 ∈ ℕ ↔ (𝑁 ∈ ℂ ∧ (𝑁 − 1) ∈ ℕ0)) | ||
| Theorem | elnnnn0b 12570 | The positive integer property expressed in terms of nonnegative integers. (Contributed by NM, 1-Sep-2005.) |
| ⊢ (𝑁 ∈ ℕ ↔ (𝑁 ∈ ℕ0 ∧ 0 < 𝑁)) | ||
| Theorem | elnnnn0c 12571 | The positive integer property expressed in terms of nonnegative integers. (Contributed by NM, 10-Jan-2006.) |
| ⊢ (𝑁 ∈ ℕ ↔ (𝑁 ∈ ℕ0 ∧ 1 ≤ 𝑁)) | ||
| Theorem | nn0addge1 12572 | A number is less than or equal to itself plus a nonnegative integer. (Contributed by NM, 10-Mar-2005.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝑁 ∈ ℕ0) → 𝐴 ≤ (𝐴 + 𝑁)) | ||
| Theorem | nn0addge2 12573 | A number is less than or equal to itself plus a nonnegative integer. (Contributed by NM, 10-Mar-2005.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝑁 ∈ ℕ0) → 𝐴 ≤ (𝑁 + 𝐴)) | ||
| Theorem | nn0addge1i 12574 | A number is less than or equal to itself plus a nonnegative integer. (Contributed by NM, 10-Mar-2005.) |
| ⊢ 𝐴 ∈ ℝ & ⊢ 𝑁 ∈ ℕ0 ⇒ ⊢ 𝐴 ≤ (𝐴 + 𝑁) | ||
| Theorem | nn0addge2i 12575 | A number is less than or equal to itself plus a nonnegative integer. (Contributed by NM, 10-Mar-2005.) |
| ⊢ 𝐴 ∈ ℝ & ⊢ 𝑁 ∈ ℕ0 ⇒ ⊢ 𝐴 ≤ (𝑁 + 𝐴) | ||
| Theorem | nn0sub 12576 | Subtraction of nonnegative integers. (Contributed by NM, 9-May-2004.) (Proof shortened by Mario Carneiro, 16-May-2014.) |
| ⊢ ((𝑀 ∈ ℕ0 ∧ 𝑁 ∈ ℕ0) → (𝑀 ≤ 𝑁 ↔ (𝑁 − 𝑀) ∈ ℕ0)) | ||
| Theorem | ltsubnn0 12577 | Subtracting a nonnegative integer from a nonnegative integer which is greater than the first one results in a nonnegative integer. (Contributed by Alexander van der Vekens, 6-Apr-2018.) |
| ⊢ ((𝐴 ∈ ℕ0 ∧ 𝐵 ∈ ℕ0) → (𝐵 < 𝐴 → (𝐴 − 𝐵) ∈ ℕ0)) | ||
| Theorem | nn0negleid 12578 | A nonnegative integer is greater than or equal to its negative. (Contributed by AV, 13-Aug-2021.) |
| ⊢ (𝐴 ∈ ℕ0 → -𝐴 ≤ 𝐴) | ||
| Theorem | difgtsumgt 12579 | If the difference of a real number and a nonnegative integer is greater than another real number, the sum of the real number and the nonnegative integer is also greater than the other real number. (Contributed by AV, 13-Aug-2021.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℕ0 ∧ 𝐶 ∈ ℝ) → (𝐶 < (𝐴 − 𝐵) → 𝐶 < (𝐴 + 𝐵))) | ||
| Theorem | nn0le2x 12580 | A nonnegative integer is less than or equal to twice itself. Generalization of nn0le2xi 12581. (Contributed by Raph Levien, 10-Dec-2002.) (Revised by AV, 9-Sep-2025.) |
| ⊢ (𝑁 ∈ ℕ0 → 𝑁 ≤ (2 · 𝑁)) | ||
| Theorem | nn0le2xi 12581 | A nonnegative integer is less than or equal to twice itself. (Contributed by Raph Levien, 10-Dec-2002.) (Proof shortened by AV, 9-Sep-2025.) |
| ⊢ 𝑁 ∈ ℕ0 ⇒ ⊢ 𝑁 ≤ (2 · 𝑁) | ||
| Theorem | nn0lele2xi 12582 | 'Less than or equal to' implies 'less than or equal to twice' for nonnegative integers. (Contributed by Raph Levien, 10-Dec-2002.) |
| ⊢ 𝑀 ∈ ℕ0 & ⊢ 𝑁 ∈ ℕ0 ⇒ ⊢ (𝑁 ≤ 𝑀 → 𝑁 ≤ (2 · 𝑀)) | ||
| Theorem | fcdmnn0supp 12583 | Two ways to write the support of a function into ℕ0. (Contributed by Mario Carneiro, 29-Dec-2014.) (Revised by AV, 7-Jul-2019.) |
| ⊢ ((𝐼 ∈ 𝑉 ∧ 𝐹:𝐼⟶ℕ0) → (𝐹 supp 0) = (◡𝐹 “ ℕ)) | ||
| Theorem | fcdmnn0fsupp 12584 | A function into ℕ0 is finitely supported iff its support is finite. (Contributed by AV, 8-Jul-2019.) |
| ⊢ ((𝐼 ∈ 𝑉 ∧ 𝐹:𝐼⟶ℕ0) → (𝐹 finSupp 0 ↔ (◡𝐹 “ ℕ) ∈ Fin)) | ||
| Theorem | fcdmnn0suppg 12585 | Version of fcdmnn0supp 12583 avoiding ax-rep 5279 by assuming 𝐹 is a set rather than its domain 𝐼. (Contributed by SN, 5-Aug-2024.) |
| ⊢ ((𝐹 ∈ 𝑉 ∧ 𝐹:𝐼⟶ℕ0) → (𝐹 supp 0) = (◡𝐹 “ ℕ)) | ||
| Theorem | fcdmnn0fsuppg 12586 | Version of fcdmnn0fsupp 12584 avoiding ax-rep 5279 by assuming 𝐹 is a set rather than its domain 𝐼. (Contributed by SN, 5-Aug-2024.) |
| ⊢ ((𝐹 ∈ 𝑉 ∧ 𝐹:𝐼⟶ℕ0) → (𝐹 finSupp 0 ↔ (◡𝐹 “ ℕ) ∈ Fin)) | ||
| Theorem | nnnn0d 12587 | A positive integer is a nonnegative integer. (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℕ) ⇒ ⊢ (𝜑 → 𝐴 ∈ ℕ0) | ||
| Theorem | nn0red 12588 | A nonnegative integer is a real number. (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℕ0) ⇒ ⊢ (𝜑 → 𝐴 ∈ ℝ) | ||
| Theorem | nn0cnd 12589 | A nonnegative integer is a complex number. (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℕ0) ⇒ ⊢ (𝜑 → 𝐴 ∈ ℂ) | ||
| Theorem | nn0ge0d 12590 | A nonnegative integer is greater than or equal to zero. (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℕ0) ⇒ ⊢ (𝜑 → 0 ≤ 𝐴) | ||
| Theorem | nn0addcld 12591 | Closure of addition of nonnegative integers, inference form. (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℕ0) & ⊢ (𝜑 → 𝐵 ∈ ℕ0) ⇒ ⊢ (𝜑 → (𝐴 + 𝐵) ∈ ℕ0) | ||
| Theorem | nn0mulcld 12592 | Closure of multiplication of nonnegative integers, inference form. (Contributed by Mario Carneiro, 27-May-2016.) |
| ⊢ (𝜑 → 𝐴 ∈ ℕ0) & ⊢ (𝜑 → 𝐵 ∈ ℕ0) ⇒ ⊢ (𝜑 → (𝐴 · 𝐵) ∈ ℕ0) | ||
| Theorem | nn0readdcl 12593 | Closure law for addition of reals, restricted to nonnegative integers. (Contributed by Alexander van der Vekens, 6-Apr-2018.) |
| ⊢ ((𝐴 ∈ ℕ0 ∧ 𝐵 ∈ ℕ0) → (𝐴 + 𝐵) ∈ ℝ) | ||
| Theorem | nn0n0n1ge2 12594 | A nonnegative integer which is neither 0 nor 1 is greater than or equal to 2. (Contributed by Alexander van der Vekens, 6-Dec-2017.) |
| ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑁 ≠ 0 ∧ 𝑁 ≠ 1) → 2 ≤ 𝑁) | ||
| Theorem | nn0n0n1ge2b 12595 | A nonnegative integer is neither 0 nor 1 if and only if it is greater than or equal to 2. (Contributed by Alexander van der Vekens, 17-Jan-2018.) |
| ⊢ (𝑁 ∈ ℕ0 → ((𝑁 ≠ 0 ∧ 𝑁 ≠ 1) ↔ 2 ≤ 𝑁)) | ||
| Theorem | nn0ge2m1nn 12596 | If a nonnegative integer is greater than or equal to two, the integer decreased by 1 is a positive integer. (Contributed by Alexander van der Vekens, 1-Aug-2018.) (Revised by AV, 4-Jan-2020.) |
| ⊢ ((𝑁 ∈ ℕ0 ∧ 2 ≤ 𝑁) → (𝑁 − 1) ∈ ℕ) | ||
| Theorem | nn0ge2m1nn0 12597 | If a nonnegative integer is greater than or equal to two, the integer decreased by 1 is also a nonnegative integer. (Contributed by Alexander van der Vekens, 1-Aug-2018.) |
| ⊢ ((𝑁 ∈ ℕ0 ∧ 2 ≤ 𝑁) → (𝑁 − 1) ∈ ℕ0) | ||
| Theorem | nn0nndivcl 12598 | Closure law for dividing of a nonnegative integer by a positive integer. (Contributed by Alexander van der Vekens, 14-Apr-2018.) |
| ⊢ ((𝐾 ∈ ℕ0 ∧ 𝐿 ∈ ℕ) → (𝐾 / 𝐿) ∈ ℝ) | ||
The function values of the hash (set size) function are either nonnegative integers or positive infinity, see hashf 14377. To avoid the need to distinguish between finite and infinite sets (and therefore if the set size is a nonnegative integer or positive infinity), it is useful to provide a definition of the set of nonnegative integers extended by positive infinity, analogously to the extension of the real numbers ℝ*, see df-xr 11299. The definition of extended nonnegative integers can be used in Ramsey theory, because the Ramsey number is either a nonnegative integer or plus infinity, see ramcl2 17054, or for the degree of polynomials, see mdegcl 26108, or for the degree of vertices in graph theory, see vtxdgf 29489. | ||
| Syntax | cxnn0 12599 | The set of extended nonnegative integers. |
| class ℕ0* | ||
| Definition | df-xnn0 12600 | Define the set of extended nonnegative integers that includes positive infinity. Analogue of the extension of the real numbers ℝ*, see df-xr 11299. (Contributed by AV, 10-Dec-2020.) |
| ⊢ ℕ0* = (ℕ0 ∪ {+∞}) | ||
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