P. 114 of Theorem List - Metamath Proof Explorer

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**Theorem List for Metamath Proof Explorer -** 11301-11400 *Has distinct variable group(s)
Type	Label	Description
Statement

Definition	df-le 11301	Define 'less than or equal to' on the extended real subset of complex numbers. Theorem leloe 11347 relates it to 'less than' for reals. (Contributed by NM, 13-Oct-2005.)
⊢ ≤ = ((ℝ^* × ℝ^*) ∖ ^◡ < )

Theorem	pnfnre 11302	Plus infinity is not a real number. (Contributed by NM, 13-Oct-2005.)
⊢ +∞ ∉ ℝ

Theorem	pnfnre2 11303	Plus infinity is not a real number. (Contributed by Glauco Siliprandi, 23-Oct-2021.)
⊢ ¬ +∞ ∈ ℝ

Theorem	mnfnre 11304	Minus infinity is not a real number. (Contributed by NM, 13-Oct-2005.)
⊢ -∞ ∉ ℝ

Theorem	ressxr 11305	The standard reals are a subset of the extended reals. (Contributed by NM, 14-Oct-2005.)
⊢ ℝ ⊆ ℝ^*

Theorem	rexpssxrxp 11306	The Cartesian product of standard reals are a subset of the Cartesian product of extended reals. (Contributed by David A. Wheeler, 8-Dec-2018.)
⊢ (ℝ × ℝ) ⊆ (ℝ^* × ℝ^*)

Theorem	rexr 11307	A standard real is an extended real. (Contributed by NM, 14-Oct-2005.)
⊢ (𝐴 ∈ ℝ → 𝐴 ∈ ℝ^*)

Theorem	0xr 11308	Zero is an extended real. (Contributed by Mario Carneiro, 15-Jun-2014.)
⊢ 0 ∈ ℝ^*

Theorem	renepnf 11309	No (finite) real equals plus infinity. (Contributed by NM, 14-Oct-2005.) (Proof shortened by Andrew Salmon, 19-Nov-2011.)
⊢ (𝐴 ∈ ℝ → 𝐴 ≠ +∞)

Theorem	renemnf 11310	No real equals minus infinity. (Contributed by NM, 14-Oct-2005.) (Proof shortened by Andrew Salmon, 19-Nov-2011.)
⊢ (𝐴 ∈ ℝ → 𝐴 ≠ -∞)

Theorem	rexrd 11311	A standard real is an extended real. (Contributed by Mario Carneiro, 28-May-2016.)
⊢ (𝜑 → 𝐴 ∈ ℝ) ⇒ ⊢ (𝜑 → 𝐴 ∈ ℝ^*)

Theorem	renepnfd 11312	No (finite) real equals plus infinity. (Contributed by Mario Carneiro, 28-May-2016.)
⊢ (𝜑 → 𝐴 ∈ ℝ) ⇒ ⊢ (𝜑 → 𝐴 ≠ +∞)

Theorem	renemnfd 11313	No real equals minus infinity. (Contributed by Mario Carneiro, 28-May-2016.)
⊢ (𝜑 → 𝐴 ∈ ℝ) ⇒ ⊢ (𝜑 → 𝐴 ≠ -∞)

Theorem	pnfex 11314	Plus infinity exists. (Contributed by David A. Wheeler, 8-Dec-2018.) (Revised by Steven Nguyen, 7-Dec-2022.)
⊢ +∞ ∈ V

Theorem	pnfxr 11315	Plus infinity belongs to the set of extended reals. (Contributed by NM, 13-Oct-2005.) (Proof shortened by Anthony Hart, 29-Aug-2011.)
⊢ +∞ ∈ ℝ^*

Theorem	pnfnemnf 11316	Plus and minus infinity are different elements of ℝ^*. (Contributed by NM, 14-Oct-2005.)
⊢ +∞ ≠ -∞

Theorem	mnfnepnf 11317	Minus and plus infinity are different. (Contributed by David A. Wheeler, 8-Dec-2018.)
⊢ -∞ ≠ +∞

Theorem	mnfxr 11318	Minus infinity belongs to the set of extended reals. (Contributed by NM, 13-Oct-2005.) (Proof shortened by Anthony Hart, 29-Aug-2011.) (Proof shortened by Andrew Salmon, 19-Nov-2011.)
⊢ -∞ ∈ ℝ^*

Theorem	rexri 11319	A standard real is an extended real (inference form.) (Contributed by David Moews, 28-Feb-2017.)
⊢ 𝐴 ∈ ℝ ⇒ ⊢ 𝐴 ∈ ℝ^*

Theorem	1xr 11320	1 is an extended real number. (Contributed by Glauco Siliprandi, 2-Jan-2022.)
⊢ 1 ∈ ℝ^*

Theorem	renfdisj 11321	The reals and the infinities are disjoint. (Contributed by NM, 25-Oct-2005.) (Proof shortened by Andrew Salmon, 19-Nov-2011.)
⊢ (ℝ ∩ {+∞, -∞}) = ∅

Theorem	ltrelxr 11322	"Less than" is a relation on extended reals. (Contributed by Mario Carneiro, 28-Apr-2015.)
⊢ < ⊆ (ℝ^* × ℝ^*)

Theorem	ltrel 11323	"Less than" is a relation. (Contributed by NM, 14-Oct-2005.)
⊢ Rel <

Theorem	lerelxr 11324	"Less than or equal to" is a relation on extended reals. (Contributed by Mario Carneiro, 28-Apr-2015.)
⊢ ≤ ⊆ (ℝ^* × ℝ^*)

Theorem	lerel 11325	"Less than or equal to" is a relation. (Contributed by FL, 2-Aug-2009.) (Revised by Mario Carneiro, 28-Apr-2015.)
⊢ Rel ≤

Theorem	xrlenlt 11326	"Less than or equal to" expressed in terms of "less than", for extended reals. (Contributed by NM, 14-Oct-2005.)
⊢ ((𝐴 ∈ ℝ^* ∧ 𝐵 ∈ ℝ^*) → (𝐴 ≤ 𝐵 ↔ ¬ 𝐵 < 𝐴))

Theorem	xrlenltd 11327	"Less than or equal to" expressed in terms of "less than", for extended reals. (Contributed by Glauco Siliprandi, 17-Aug-2020.)
⊢ (𝜑 → 𝐴 ∈ ℝ^) & ⊢ (𝜑 → 𝐵 ∈ ℝ^) ⇒ ⊢ (𝜑 → (𝐴 ≤ 𝐵 ↔ ¬ 𝐵 < 𝐴))

Theorem	xrltnle 11328	"Less than" expressed in terms of "less than or equal to", for extended reals. (Contributed by NM, 6-Feb-2007.)
⊢ ((𝐴 ∈ ℝ^* ∧ 𝐵 ∈ ℝ^*) → (𝐴 < 𝐵 ↔ ¬ 𝐵 ≤ 𝐴))

Theorem	xrnltled 11329	"Not less than" implies "less than or equal to". (Contributed by Glauco Siliprandi, 11-Dec-2019.)
⊢ (𝜑 → 𝐴 ∈ ℝ^) & ⊢ (𝜑 → 𝐵 ∈ ℝ^) & ⊢ (𝜑 → ¬ 𝐵 < 𝐴) ⇒ ⊢ (𝜑 → 𝐴 ≤ 𝐵)

Theorem	ssxr 11330	The three (non-exclusive) possibilities implied by a subset of extended reals. (Contributed by NM, 25-Oct-2005.) (Proof shortened by Andrew Salmon, 19-Nov-2011.)
⊢ (𝐴 ⊆ ℝ^* → (𝐴 ⊆ ℝ ∨ +∞ ∈ 𝐴 ∨ -∞ ∈ 𝐴))

Theorem	ltxrlt 11331	The standard less-than <_ℝ and the extended real less-than < are identical when restricted to the non-extended reals ℝ. (Contributed by NM, 13-Oct-2005.) (Revised by Mario Carneiro, 28-Apr-2015.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 < 𝐵 ↔ 𝐴 <_ℝ 𝐵))

5.2.3 Restate the ordering postulates with extended real "less than"

Theorem	axlttri 11332	Ordering on reals satisfies strict trichotomy. Axiom 18 of 22 for real and complex numbers, derived from ZF set theory. (This restates ax-pre-lttri 11229 with ordering on the extended reals.) (Contributed by NM, 13-Oct-2005.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 < 𝐵 ↔ ¬ (𝐴 = 𝐵 ∨ 𝐵 < 𝐴)))

Theorem	axlttrn 11333	Ordering on reals is transitive. Axiom 19 of 22 for real and complex numbers, derived from ZF set theory. This restates ax-pre-lttrn 11230 with ordering on the extended reals. New proofs should use lttr 11337 instead for naming consistency. (New usage is discouraged.) (Contributed by NM, 13-Oct-2005.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → ((𝐴 < 𝐵 ∧ 𝐵 < 𝐶) → 𝐴 < 𝐶))

Theorem	axltadd 11334	Ordering property of addition on reals. Axiom 20 of 22 for real and complex numbers, derived from ZF set theory. (This restates ax-pre-ltadd 11231 with ordering on the extended reals.) (Contributed by NM, 13-Oct-2005.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → (𝐴 < 𝐵 → (𝐶 + 𝐴) < (𝐶 + 𝐵)))

Theorem	axmulgt0 11335	The product of two positive reals is positive. Axiom 21 of 22 for real and complex numbers, derived from ZF set theory. (This restates ax-pre-mulgt0 11232 with ordering on the extended reals.) (Contributed by NM, 13-Oct-2005.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((0 < 𝐴 ∧ 0 < 𝐵) → 0 < (𝐴 · 𝐵)))

Theorem	axsup 11336*	A nonempty, bounded-above set of reals has a supremum. Axiom 22 of 22 for real and complex numbers, derived from ZF set theory. (This restates ax-pre-sup 11233 with ordering on the extended reals.) (Contributed by NM, 13-Oct-2005.)
⊢ ((𝐴 ⊆ ℝ ∧ 𝐴 ≠ ∅ ∧ ∃𝑥 ∈ ℝ ∀𝑦 ∈ 𝐴 𝑦 < 𝑥) → ∃𝑥 ∈ ℝ (∀𝑦 ∈ 𝐴 ¬ 𝑥 < 𝑦 ∧ ∀𝑦 ∈ ℝ (𝑦 < 𝑥 → ∃𝑧 ∈ 𝐴 𝑦 < 𝑧)))

5.2.4 Ordering on reals

Theorem	lttr 11337	Alias for axlttrn 11333, for naming consistency with lttri 11387. New proofs should generally use this instead of ax-pre-lttrn 11230. (Contributed by NM, 10-Mar-2008.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → ((𝐴 < 𝐵 ∧ 𝐵 < 𝐶) → 𝐴 < 𝐶))

Theorem	mulgt0 11338	The product of two positive numbers is positive. (Contributed by NM, 10-Mar-2008.)
⊢ (((𝐴 ∈ ℝ ∧ 0 < 𝐴) ∧ (𝐵 ∈ ℝ ∧ 0 < 𝐵)) → 0 < (𝐴 · 𝐵))

Theorem	lenlt 11339	'Less than or equal to' expressed in terms of 'less than'. (Contributed by NM, 13-May-1999.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 ≤ 𝐵 ↔ ¬ 𝐵 < 𝐴))

Theorem	ltnle 11340	'Less than' expressed in terms of 'less than or equal to'. (Contributed by NM, 11-Jul-2005.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 < 𝐵 ↔ ¬ 𝐵 ≤ 𝐴))

Theorem	ltso 11341	'Less than' is a strict ordering. (Contributed by NM, 19-Jan-1997.)
⊢ < Or ℝ

Theorem	gtso 11342	'Greater than' is a strict ordering. (Contributed by JJ, 11-Oct-2018.)
⊢ ^◡ < Or ℝ

Theorem	lttri2 11343	Consequence of trichotomy. (Contributed by NM, 9-Oct-1999.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 ≠ 𝐵 ↔ (𝐴 < 𝐵 ∨ 𝐵 < 𝐴)))

Theorem	lttri3 11344	Trichotomy law for 'less than'. (Contributed by NM, 5-May-1999.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 = 𝐵 ↔ (¬ 𝐴 < 𝐵 ∧ ¬ 𝐵 < 𝐴)))

Theorem	lttri4 11345	Trichotomy law for 'less than'. (Contributed by NM, 20-Sep-2007.) (Proof shortened by Andrew Salmon, 19-Nov-2011.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 < 𝐵 ∨ 𝐴 = 𝐵 ∨ 𝐵 < 𝐴))

Theorem	letri3 11346	Trichotomy law. (Contributed by NM, 14-May-1999.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 = 𝐵 ↔ (𝐴 ≤ 𝐵 ∧ 𝐵 ≤ 𝐴)))

Theorem	leloe 11347	'Less than or equal to' expressed in terms of 'less than' or 'equals'. (Contributed by NM, 13-May-1999.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 ≤ 𝐵 ↔ (𝐴 < 𝐵 ∨ 𝐴 = 𝐵)))

Theorem	eqlelt 11348	Equality in terms of 'less than or equal to', 'less than'. (Contributed by NM, 7-Apr-2001.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 = 𝐵 ↔ (𝐴 ≤ 𝐵 ∧ ¬ 𝐴 < 𝐵)))

Theorem	ltle 11349	'Less than' implies 'less than or equal to'. (Contributed by NM, 25-Aug-1999.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 < 𝐵 → 𝐴 ≤ 𝐵))

Theorem	leltne 11350	'Less than or equal to' implies 'less than' is not 'equals'. (Contributed by NM, 27-Jul-1999.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐴 ≤ 𝐵) → (𝐴 < 𝐵 ↔ 𝐵 ≠ 𝐴))

Theorem	lelttr 11351	Transitive law. (Contributed by NM, 23-May-1999.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → ((𝐴 ≤ 𝐵 ∧ 𝐵 < 𝐶) → 𝐴 < 𝐶))

Theorem	leltletr 11352	Transitive law, weaker form of lelttr 11351. (Contributed by AV, 14-Oct-2018.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → ((𝐴 ≤ 𝐵 ∧ 𝐵 < 𝐶) → 𝐴 ≤ 𝐶))

Theorem	ltletr 11353	Transitive law. (Contributed by NM, 25-Aug-1999.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → ((𝐴 < 𝐵 ∧ 𝐵 ≤ 𝐶) → 𝐴 < 𝐶))

Theorem	ltleletr 11354	Transitive law, weaker form of ltletr 11353. (Contributed by AV, 14-Oct-2018.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → ((𝐴 < 𝐵 ∧ 𝐵 ≤ 𝐶) → 𝐴 ≤ 𝐶))

Theorem	letr 11355	Transitive law. (Contributed by NM, 12-Nov-1999.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → ((𝐴 ≤ 𝐵 ∧ 𝐵 ≤ 𝐶) → 𝐴 ≤ 𝐶))

Theorem	ltnr 11356	'Less than' is irreflexive. (Contributed by NM, 18-Aug-1999.)
⊢ (𝐴 ∈ ℝ → ¬ 𝐴 < 𝐴)

Theorem	leid 11357	'Less than or equal to' is reflexive. (Contributed by NM, 18-Aug-1999.)
⊢ (𝐴 ∈ ℝ → 𝐴 ≤ 𝐴)

Theorem	ltne 11358	'Less than' implies not equal. (Contributed by NM, 9-Oct-1999.) (Revised by Mario Carneiro, 16-Sep-2015.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐴 < 𝐵) → 𝐵 ≠ 𝐴)

Theorem	ltnsym 11359	'Less than' is not symmetric. (Contributed by NM, 8-Jan-2002.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 < 𝐵 → ¬ 𝐵 < 𝐴))

Theorem	ltnsym2 11360	'Less than' is antisymmetric and irreflexive. (Contributed by NM, 13-Aug-2005.) (Proof shortened by Andrew Salmon, 19-Nov-2011.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ¬ (𝐴 < 𝐵 ∧ 𝐵 < 𝐴))

Theorem	letric 11361	Trichotomy law. (Contributed by NM, 18-Aug-1999.) (Proof shortened by Andrew Salmon, 19-Nov-2011.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 ≤ 𝐵 ∨ 𝐵 ≤ 𝐴))

Theorem	ltlen 11362	'Less than' expressed in terms of 'less than or equal to'. (Contributed by NM, 27-Oct-1999.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 < 𝐵 ↔ (𝐴 ≤ 𝐵 ∧ 𝐵 ≠ 𝐴)))

Theorem	eqle 11363	Equality implies 'less than or equal to'. (Contributed by NM, 4-Apr-2005.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐴 = 𝐵) → 𝐴 ≤ 𝐵)

Theorem	eqled 11364	Equality implies 'less than or equal to'. (Contributed by Glauco Siliprandi, 11-Dec-2019.)
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐴 = 𝐵) ⇒ ⊢ (𝜑 → 𝐴 ≤ 𝐵)

Theorem	ltadd2 11365	Addition to both sides of 'less than'. (Contributed by NM, 12-Nov-1999.) (Revised by Mario Carneiro, 27-May-2016.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → (𝐴 < 𝐵 ↔ (𝐶 + 𝐴) < (𝐶 + 𝐵)))

Theorem	ne0gt0 11366	A nonzero nonnegative number is positive. (Contributed by NM, 20-Nov-2007.)
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (𝐴 ≠ 0 ↔ 0 < 𝐴))

Theorem	lecasei 11367	Ordering elimination by cases. (Contributed by NM, 6-Jul-2007.)
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) & ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐵) → 𝜓) & ⊢ ((𝜑 ∧ 𝐵 ≤ 𝐴) → 𝜓) ⇒ ⊢ (𝜑 → 𝜓)

Theorem	lelttric 11368	Trichotomy law. (Contributed by NM, 4-Apr-2005.)
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 ≤ 𝐵 ∨ 𝐵 < 𝐴))

Theorem	ltlecasei 11369	Ordering elimination by cases. (Contributed by NM, 1-Jul-2007.) (Proof shortened by Mario Carneiro, 27-May-2016.)
⊢ ((𝜑 ∧ 𝐴 < 𝐵) → 𝜓) & ⊢ ((𝜑 ∧ 𝐵 ≤ 𝐴) → 𝜓) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) ⇒ ⊢ (𝜑 → 𝜓)

Theorem	ltnri 11370	'Less than' is irreflexive. (Contributed by NM, 18-Aug-1999.)
⊢ 𝐴 ∈ ℝ ⇒ ⊢ ¬ 𝐴 < 𝐴

Theorem	eqlei 11371	Equality implies 'less than or equal to'. (Contributed by NM, 23-May-1999.) (Revised by Alexander van der Vekens, 20-Mar-2018.)
⊢ 𝐴 ∈ ℝ ⇒ ⊢ (𝐴 = 𝐵 → 𝐴 ≤ 𝐵)

Theorem	eqlei2 11372	Equality implies 'less than or equal to'. (Contributed by Alexander van der Vekens, 20-Mar-2018.)
⊢ 𝐴 ∈ ℝ ⇒ ⊢ (𝐵 = 𝐴 → 𝐵 ≤ 𝐴)

Theorem	gtneii 11373	'Less than' implies not equal. (Contributed by Mario Carneiro, 30-Sep-2013.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐴 < 𝐵 ⇒ ⊢ 𝐵 ≠ 𝐴

Theorem	ltneii 11374	'Greater than' implies not equal. (Contributed by Mario Carneiro, 16-Sep-2015.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐴 < 𝐵 ⇒ ⊢ 𝐴 ≠ 𝐵

Theorem	lttri2i 11375	Consequence of trichotomy. (Contributed by NM, 19-Jan-1997.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ (𝐴 ≠ 𝐵 ↔ (𝐴 < 𝐵 ∨ 𝐵 < 𝐴))

Theorem	lttri3i 11376	Consequence of trichotomy. (Contributed by NM, 14-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ (𝐴 = 𝐵 ↔ (¬ 𝐴 < 𝐵 ∧ ¬ 𝐵 < 𝐴))

Theorem	letri3i 11377	Consequence of trichotomy. (Contributed by NM, 14-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ (𝐴 = 𝐵 ↔ (𝐴 ≤ 𝐵 ∧ 𝐵 ≤ 𝐴))

Theorem	leloei 11378	'Less than or equal to' in terms of 'less than'. (Contributed by NM, 14-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ (𝐴 ≤ 𝐵 ↔ (𝐴 < 𝐵 ∨ 𝐴 = 𝐵))

Theorem	ltleni 11379	'Less than' expressed in terms of 'less than or equal to'. (Contributed by NM, 27-Oct-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ (𝐴 < 𝐵 ↔ (𝐴 ≤ 𝐵 ∧ 𝐵 ≠ 𝐴))

Theorem	ltnsymi 11380	'Less than' is not symmetric. (Contributed by NM, 6-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ (𝐴 < 𝐵 → ¬ 𝐵 < 𝐴)

Theorem	lenlti 11381	'Less than or equal to' in terms of 'less than'. (Contributed by NM, 24-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ (𝐴 ≤ 𝐵 ↔ ¬ 𝐵 < 𝐴)

Theorem	ltnlei 11382	'Less than' in terms of 'less than or equal to'. (Contributed by NM, 11-Jul-2005.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ (𝐴 < 𝐵 ↔ ¬ 𝐵 ≤ 𝐴)

Theorem	ltlei 11383	'Less than' implies 'less than or equal to'. (Contributed by NM, 14-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ (𝐴 < 𝐵 → 𝐴 ≤ 𝐵)

Theorem	ltleii 11384	'Less than' implies 'less than or equal to' (inference). (Contributed by NM, 22-Aug-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ & ⊢ 𝐴 < 𝐵 ⇒ ⊢ 𝐴 ≤ 𝐵

Theorem	ltnei 11385	'Less than' implies not equal. (Contributed by NM, 28-Jul-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ (𝐴 < 𝐵 → 𝐵 ≠ 𝐴)

Theorem	letrii 11386	Trichotomy law for 'less than or equal to'. (Contributed by NM, 2-Aug-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ (𝐴 ≤ 𝐵 ∨ 𝐵 ≤ 𝐴)

Theorem	lttri 11387	'Less than' is transitive. Theorem I.17 of [Apostol] p. 20. (Contributed by NM, 14-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ & ⊢ 𝐶 ∈ ℝ ⇒ ⊢ ((𝐴 < 𝐵 ∧ 𝐵 < 𝐶) → 𝐴 < 𝐶)

Theorem	lelttri 11388	'Less than or equal to', 'less than' transitive law. (Contributed by NM, 14-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ & ⊢ 𝐶 ∈ ℝ ⇒ ⊢ ((𝐴 ≤ 𝐵 ∧ 𝐵 < 𝐶) → 𝐴 < 𝐶)

Theorem	ltletri 11389	'Less than', 'less than or equal to' transitive law. (Contributed by NM, 14-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ & ⊢ 𝐶 ∈ ℝ ⇒ ⊢ ((𝐴 < 𝐵 ∧ 𝐵 ≤ 𝐶) → 𝐴 < 𝐶)

Theorem	letri 11390	'Less than or equal to' is transitive. (Contributed by NM, 14-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ & ⊢ 𝐶 ∈ ℝ ⇒ ⊢ ((𝐴 ≤ 𝐵 ∧ 𝐵 ≤ 𝐶) → 𝐴 ≤ 𝐶)

Theorem	le2tri3i 11391	Extended trichotomy law for 'less than or equal to'. (Contributed by NM, 14-Aug-2000.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ & ⊢ 𝐶 ∈ ℝ ⇒ ⊢ ((𝐴 ≤ 𝐵 ∧ 𝐵 ≤ 𝐶 ∧ 𝐶 ≤ 𝐴) ↔ (𝐴 = 𝐵 ∧ 𝐵 = 𝐶 ∧ 𝐶 = 𝐴))

Theorem	ltadd2i 11392	Addition to both sides of 'less than'. (Contributed by NM, 21-Jan-1997.) (Proof shortened by OpenAI, 25-Mar-2020.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ & ⊢ 𝐶 ∈ ℝ ⇒ ⊢ (𝐴 < 𝐵 ↔ (𝐶 + 𝐴) < (𝐶 + 𝐵))

Theorem	mulgt0i 11393	The product of two positive numbers is positive. (Contributed by NM, 16-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ ⇒ ⊢ ((0 < 𝐴 ∧ 0 < 𝐵) → 0 < (𝐴 · 𝐵))

Theorem	mulgt0ii 11394	The product of two positive numbers is positive. (Contributed by NM, 18-May-1999.)
⊢ 𝐴 ∈ ℝ & ⊢ 𝐵 ∈ ℝ & ⊢ 0 < 𝐴 & ⊢ 0 < 𝐵 ⇒ ⊢ 0 < (𝐴 · 𝐵)

Theorem	ltnrd 11395	'Less than' is irreflexive. (Contributed by Mario Carneiro, 27-May-2016.)
⊢ (𝜑 → 𝐴 ∈ ℝ) ⇒ ⊢ (𝜑 → ¬ 𝐴 < 𝐴)

Theorem	gtned 11396	'Less than' implies not equal. (Contributed by Mario Carneiro, 27-May-2016.)
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐴 < 𝐵) ⇒ ⊢ (𝜑 → 𝐵 ≠ 𝐴)

Theorem	ltned 11397	'Greater than' implies not equal. (Contributed by Mario Carneiro, 27-May-2016.)
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐴 < 𝐵) ⇒ ⊢ (𝜑 → 𝐴 ≠ 𝐵)

Theorem	ne0gt0d 11398	A nonzero nonnegative number is positive. (Contributed by Mario Carneiro, 27-May-2016.)
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 0 ≤ 𝐴) & ⊢ (𝜑 → 𝐴 ≠ 0) ⇒ ⊢ (𝜑 → 0 < 𝐴)

Theorem	lttrid 11399	Ordering on reals satisfies strict trichotomy. (Contributed by Mario Carneiro, 27-May-2016.)
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) ⇒ ⊢ (𝜑 → (𝐴 < 𝐵 ↔ ¬ (𝐴 = 𝐵 ∨ 𝐵 < 𝐴)))

Theorem	lttri2d 11400	Consequence of trichotomy. (Contributed by Mario Carneiro, 27-May-2016.)
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) ⇒ ⊢ (𝜑 → (𝐴 ≠ 𝐵 ↔ (𝐴 < 𝐵 ∨ 𝐵 < 𝐴)))

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