P. 331 of Theorem List - Metamath Proof Explorer

Theorem List for Metamath Proof Explorer - 33001-33100   *Has distinct variable group(s)

Type	Label	Description
Statement
Theorem	erlbr2d 33001	Deduce the ring localization equivalence relation. Pairs ⟨𝐸, 𝐺⟩ and ⟨𝑇 · 𝐸, 𝑇 · 𝐺⟩ for 𝑇 ∈ 𝑆 are equivalent under the localization relation. (Contributed by Thierry Arnoux, 4-May-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ ∼ = (𝑅 ~RL 𝑆)    &   ⊢ (𝜑 → 𝑅 ∈ CRing)    &   ⊢ (𝜑 → 𝑆 ∈ (SubMnd‘(mulGrp‘𝑅)))    &   ⊢ · = (.r‘𝑅)    &   ⊢ (𝜑 → 𝑈 = ⟨𝐸, 𝐺⟩)    &   ⊢ (𝜑 → 𝑉 = ⟨𝐹, 𝐻⟩)    &   ⊢ (𝜑 → 𝐸 ∈ 𝐵)    &   ⊢ (𝜑 → 𝐹 ∈ 𝐵)    &   ⊢ (𝜑 → 𝐺 ∈ 𝑆)    &   ⊢ (𝜑 → 𝐻 ∈ 𝑆)    &   ⊢ (𝜑 → 𝑇 ∈ 𝑆)    &   ⊢ (𝜑 → 𝐹 = (𝑇 · 𝐸))    &   ⊢ (𝜑 → 𝐻 = (𝑇 · 𝐺))    ⇒   ⊢ (𝜑 → 𝑈 ∼ 𝑉)
Theorem	erler 33002	The relation used to build the ring localization is an equivalence relation. (Contributed by Thierry Arnoux, 4-May-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ 1 = (1r‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ − = (-g‘𝑅)    &   ⊢ 𝑊 = (𝐵 × 𝑆)    &   ⊢ ∼ = (𝑅 ~RL 𝑆)    &   ⊢ (𝜑 → 𝑅 ∈ CRing)    &   ⊢ (𝜑 → 𝑆 ∈ (SubMnd‘(mulGrp‘𝑅)))    ⇒   ⊢ (𝜑 → ∼ Er 𝑊)
Theorem	elrlocbasi 33003*	Membership in the basis of a ring localization. (Contributed by Thierry Arnoux, 4-May-2025.)
⊢ (𝜑 → 𝑋 ∈ ((𝐵 × 𝑆) / ∼ ))    ⇒   ⊢ (𝜑 → ∃𝑎 ∈ 𝐵 ∃𝑏 ∈ 𝑆 𝑋 = [⟨𝑎, 𝑏⟩] ∼ )
Theorem	rlocbas 33004	The base set of a ring localization. (Contributed by Thierry Arnoux, 4-May-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ − = (-g‘𝑅)    &   ⊢ 𝑊 = (𝐵 × 𝑆)    &   ⊢ 𝐿 = (𝑅 RLocal 𝑆)    &   ⊢ ∼ = (𝑅 ~RL 𝑆)    &   ⊢ (𝜑 → 𝑅 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑆 ⊆ 𝐵)    ⇒   ⊢ (𝜑 → (𝑊 / ∼ ) = (Base‘𝐿))
Theorem	rlocaddval 33005	Value of the addition in the ring localization, given two representatives. (Contributed by Thierry Arnoux, 4-May-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ + = (+g‘𝑅)    &   ⊢ 𝐿 = (𝑅 RLocal 𝑆)    &   ⊢ ∼ = (𝑅 ~RL 𝑆)    &   ⊢ (𝜑 → 𝑅 ∈ CRing)    &   ⊢ (𝜑 → 𝑆 ∈ (SubMnd‘(mulGrp‘𝑅)))    &   ⊢ (𝜑 → 𝐸 ∈ 𝐵)    &   ⊢ (𝜑 → 𝐹 ∈ 𝐵)    &   ⊢ (𝜑 → 𝐺 ∈ 𝑆)    &   ⊢ (𝜑 → 𝐻 ∈ 𝑆)    &   ⊢ ⊕ = (+g‘𝐿)    ⇒   ⊢ (𝜑 → ([⟨𝐸, 𝐺⟩] ∼ ⊕ [⟨𝐹, 𝐻⟩] ∼ ) = [⟨((𝐸 · 𝐻) + (𝐹 · 𝐺)), (𝐺 · 𝐻)⟩] ∼ )
Theorem	rlocmulval 33006	Value of the addition in the ring localization, given two representatives. (Contributed by Thierry Arnoux, 4-May-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ + = (+g‘𝑅)    &   ⊢ 𝐿 = (𝑅 RLocal 𝑆)    &   ⊢ ∼ = (𝑅 ~RL 𝑆)    &   ⊢ (𝜑 → 𝑅 ∈ CRing)    &   ⊢ (𝜑 → 𝑆 ∈ (SubMnd‘(mulGrp‘𝑅)))    &   ⊢ (𝜑 → 𝐸 ∈ 𝐵)    &   ⊢ (𝜑 → 𝐹 ∈ 𝐵)    &   ⊢ (𝜑 → 𝐺 ∈ 𝑆)    &   ⊢ (𝜑 → 𝐻 ∈ 𝑆)    &   ⊢ ⊗ = (.r‘𝐿)    ⇒   ⊢ (𝜑 → ([⟨𝐸, 𝐺⟩] ∼ ⊗ [⟨𝐹, 𝐻⟩] ∼ ) = [⟨(𝐸 · 𝐹), (𝐺 · 𝐻)⟩] ∼ )
Theorem	rloccring 33007	The ring localization 𝐿 of a commutative ring 𝑅 by a multiplicatively closed set 𝑆 is itself a commutative ring. (Contributed by Thierry Arnoux, 4-May-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ + = (+g‘𝑅)    &   ⊢ 𝐿 = (𝑅 RLocal 𝑆)    &   ⊢ ∼ = (𝑅 ~RL 𝑆)    &   ⊢ (𝜑 → 𝑅 ∈ CRing)    &   ⊢ (𝜑 → 𝑆 ∈ (SubMnd‘(mulGrp‘𝑅)))    ⇒   ⊢ (𝜑 → 𝐿 ∈ CRing)
Theorem	rloc0g 33008	The zero of a ring localization. (Contributed by Thierry Arnoux, 4-May-2025.)
⊢ 0 = (0g‘𝑅)    &   ⊢ 1 = (1r‘𝑅)    &   ⊢ 𝐿 = (𝑅 RLocal 𝑆)    &   ⊢ ∼ = (𝑅 ~RL 𝑆)    &   ⊢ (𝜑 → 𝑅 ∈ CRing)    &   ⊢ (𝜑 → 𝑆 ∈ (SubMnd‘(mulGrp‘𝑅)))    &   ⊢ 𝑂 = [⟨ 0 , 1 ⟩] ∼    ⇒   ⊢ (𝜑 → 𝑂 = (0g‘𝐿))
Theorem	rloc1r 33009	The multiplicative identity of a ring localization. (Contributed by Thierry Arnoux, 4-May-2025.)
⊢ 0 = (0g‘𝑅)    &   ⊢ 1 = (1r‘𝑅)    &   ⊢ 𝐿 = (𝑅 RLocal 𝑆)    &   ⊢ ∼ = (𝑅 ~RL 𝑆)    &   ⊢ (𝜑 → 𝑅 ∈ CRing)    &   ⊢ (𝜑 → 𝑆 ∈ (SubMnd‘(mulGrp‘𝑅)))    &   ⊢ 𝐼 = [⟨ 1 , 1 ⟩] ∼    ⇒   ⊢ (𝜑 → 𝐼 = (1r‘𝐿))
Theorem	rlocf1 33010*	The embedding 𝐹 of a ring 𝑅 into its localization 𝐿. (Contributed by Thierry Arnoux, 4-May-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 1 = (1r‘𝑅)    &   ⊢ 𝐿 = (𝑅 RLocal 𝑆)    &   ⊢ ∼ = (𝑅 ~RL 𝑆)    &   ⊢ 𝐹 = (𝑥 ∈ 𝐵 ↦ [⟨𝑥, 1 ⟩] ∼ )    &   ⊢ (𝜑 → 𝑅 ∈ CRing)    &   ⊢ (𝜑 → 𝑆 ∈ (SubMnd‘(mulGrp‘𝑅)))    &   ⊢ (𝜑 → 𝑆 ⊆ (RLReg‘𝑅))    ⇒   ⊢ (𝜑 → (𝐹:𝐵–1-1→((𝐵 × 𝑆) / ∼ ) ∧ 𝐹 ∈ (𝑅 RingHom 𝐿)))
21.3.9.18  Integral Domains
Theorem	domnlcan 33011	Left-cancellation law for domains. (Contributed by Thierry Arnoux, 22-Mar-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ (𝜑 → 𝑋 ∈ (𝐵 ∖ { 0 }))    &   ⊢ (𝜑 → 𝑌 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑍 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑅 ∈ Domn)    &   ⊢ (𝜑 → (𝑋 · 𝑌) = (𝑋 · 𝑍))    ⇒   ⊢ (𝜑 → 𝑌 = 𝑍)
Theorem	idomrcan 33012	Right-cancellation law for integral domains. (Contributed by Thierry Arnoux, 22-Mar-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ (𝜑 → 𝑋 ∈ (𝐵 ∖ { 0 }))    &   ⊢ (𝜑 → 𝑌 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑍 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑅 ∈ IDomn)    &   ⊢ (𝜑 → (𝑌 · 𝑋) = (𝑍 · 𝑋))    ⇒   ⊢ (𝜑 → 𝑌 = 𝑍)
Theorem	1rrg 33013	The multiplicative identity is a left-regular element. (Contributed by Thierry Arnoux, 6-May-2025.)
⊢ 1 = (1r‘𝑅)    &   ⊢ 𝐸 = (RLReg‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ Ring)    ⇒   ⊢ (𝜑 → 1 ∈ 𝐸)
Theorem	rrgnz 33014	In a non-zero ring, the zero is not a nonzero-divisors. (Contributed by Thierry Arnoux, 6-May-2025.)
⊢ 𝐸 = (RLReg‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    ⇒   ⊢ (𝑅 ∈ NzRing → ¬ 0 ∈ 𝐸)
Theorem	isdomn6 33015	A ring is a domain iff nonzero-divisors are all the nonzero elements. (Contributed by Thierry Arnoux, 6-May-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 𝐸 = (RLReg‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    ⇒   ⊢ (𝑅 ∈ Domn ↔ (𝑅 ∈ NzRing ∧ (𝐵 ∖ { 0 }) = 𝐸))
Theorem	rrgsubm 33016	The left regular elements of a ring form a submonoid of the multiplicative group. (Contributed by Thierry Arnoux, 10-May-2025.)
⊢ 𝐸 = (RLReg‘𝑅)    &   ⊢ 𝑀 = (mulGrp‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ Ring)    ⇒   ⊢ (𝜑 → 𝐸 ∈ (SubMnd‘𝑀))
Theorem	subrdom 33017	A subring of a domain is a domain. (Contributed by Thierry Arnoux, 18-May-2025.)
⊢ (𝜑 → 𝑅 ∈ Domn)    &   ⊢ (𝜑 → 𝑆 ∈ (SubRing‘𝑅))    ⇒   ⊢ (𝜑 → (𝑅 ↾s 𝑆) ∈ Domn)
Theorem	subridom 33018	A subring of an integral domain is an integral domain. (Contributed by Thierry Arnoux, 18-May-2025.)
⊢ (𝜑 → 𝑅 ∈ IDomn)    &   ⊢ (𝜑 → 𝑆 ∈ (SubRing‘𝑅))    ⇒   ⊢ (𝜑 → (𝑅 ↾s 𝑆) ∈ IDomn)
Theorem	subrfld 33019	A subring of a field is an integral domain. (Contributed by Thierry Arnoux, 18-May-2025.)
⊢ (𝜑 → 𝑅 ∈ Field)    &   ⊢ (𝜑 → 𝑆 ∈ (SubRing‘𝑅))    ⇒   ⊢ (𝜑 → (𝑅 ↾s 𝑆) ∈ IDomn)
21.3.9.19  Euclidean Domains
Syntax	ceuf 33020	Declare the syntax for the Euclidean function index extractor.
class EuclF
Definition	df-euf 33021	Define the Euclidean function. (Contributed by Thierry Arnoux, 22-Mar-2025.) Use its index-independent form eufid 33023 instead. (New usage is discouraged.)
⊢ EuclF = Slot ;21
Theorem	eufndx 33022	Index value of the Euclidean function slot. Use ndxarg 17159. (Contributed by Thierry Arnoux, 22-Mar-2025.) (New usage is discouraged.)
⊢ (EuclF‘ndx) = ;21
Theorem	eufid 33023	Utility theorem: index-independent form of df-euf 33021. (Contributed by Thierry Arnoux, 22-Mar-2025.)
⊢ EuclF = Slot (EuclF‘ndx)
Syntax	cedom 33024	Declare the syntax for the Euclidean Domain.
class EDomn
Definition	df-edom 33025*	Define Euclidean Domains. (Contributed by Thierry Arnoux, 22-Mar-2025.)
⊢ EDomn = {𝑑 ∈ IDomn ∣ [(EuclF‘𝑑) / 𝑒][(Base‘𝑑) / 𝑣](Fun 𝑒 ∧ (𝑒 “ (𝑣 ∖ {(0g‘𝑑)})) ⊆ (0[,)+∞) ∧ ∀𝑎 ∈ 𝑣 ∀𝑏 ∈ (𝑣 ∖ {(0g‘𝑑)})∃𝑞 ∈ 𝑣 ∃𝑟 ∈ 𝑣 (𝑎 = ((𝑏(.r‘𝑑)𝑞)(+g‘𝑑)𝑟) ∧ (𝑟 = (0g‘𝑑) ∨ (𝑒‘𝑟) < (𝑒‘𝑏))))}
21.3.9.20  Division Rings
Theorem	ringinveu 33026	If a ring unit element 𝑋 admits both a left inverse 𝑌 and a right inverse 𝑍, they are equal. (Contributed by Thierry Arnoux, 9-Mar-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ 1 = (1r‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ 𝑈 = (Unit‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ Ring)    &   ⊢ (𝜑 → 𝑋 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑌 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑍 ∈ 𝐵)    &   ⊢ (𝜑 → (𝑌 · 𝑋) = 1 )    &   ⊢ (𝜑 → (𝑋 · 𝑍) = 1 )    ⇒   ⊢ (𝜑 → 𝑍 = 𝑌)
Theorem	isdrng4 33027*	A division ring is a ring in which 1 ≠ 0 and every nonzero element has a left and right inverse. (Contributed by Thierry Arnoux, 2-Mar-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ 1 = (1r‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ 𝑈 = (Unit‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ Ring)    ⇒   ⊢ (𝜑 → (𝑅 ∈ DivRing ↔ ( 1 ≠ 0 ∧ ∀𝑥 ∈ (𝐵 ∖ { 0 })∃𝑦 ∈ 𝐵 ((𝑥 · 𝑦) = 1 ∧ (𝑦 · 𝑥) = 1 ))))
Theorem	rndrhmcl 33028	The image of a division ring by a ring homomorphism is a division ring. (Contributed by Thierry Arnoux, 25-Feb-2025.)
⊢ 𝑅 = (𝑁 ↾s ran 𝐹)    &   ⊢ 0 = (0g‘𝑁)    &   ⊢ (𝜑 → 𝐹 ∈ (𝑀 RingHom 𝑁))    &   ⊢ (𝜑 → ran 𝐹 ≠ { 0 })    &   ⊢ (𝜑 → 𝑀 ∈ DivRing)    ⇒   ⊢ (𝜑 → 𝑅 ∈ DivRing)
21.3.9.21  Subfields
Theorem	sdrgdvcl 33029	A sub-division-ring is closed under the ring division operation. (Contributed by Thierry Arnoux, 15-Jan-2025.)
⊢ / = (/r‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ (𝜑 → 𝐴 ∈ (SubDRing‘𝑅))    &   ⊢ (𝜑 → 𝑋 ∈ 𝐴)    &   ⊢ (𝜑 → 𝑌 ∈ 𝐴)    &   ⊢ (𝜑 → 𝑌 ≠ 0 )    ⇒   ⊢ (𝜑 → (𝑋 / 𝑌) ∈ 𝐴)
Theorem	sdrginvcl 33030	A sub-division-ring is closed under the ring inverse operation. (Contributed by Thierry Arnoux, 15-Jan-2025.)
⊢ 𝐼 = (invr‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    ⇒   ⊢ ((𝐴 ∈ (SubDRing‘𝑅) ∧ 𝑋 ∈ 𝐴 ∧ 𝑋 ≠ 0 ) → (𝐼‘𝑋) ∈ 𝐴)
Theorem	primefldchr 33031	The characteristic of a prime field is the same as the characteristic of the main field. (Contributed by Thierry Arnoux, 21-Aug-2023.)
⊢ 𝑃 = (𝑅 ↾s ∩ (SubDRing‘𝑅))    ⇒   ⊢ (𝑅 ∈ DivRing → (chr‘𝑃) = (chr‘𝑅))
21.3.9.22  Field of fractions
Syntax	cfrac 33032	Syntax for the field of fractions of a given integral domain.
class Frac
Definition	df-frac 33033	Define the field of fractions of a given integral domain. (Contributed by Thierry Arnoux, 26-Apr-2025.)
⊢ Frac = (𝑟 ∈ V ↦ (𝑟 RLocal (RLReg‘𝑟)))
Theorem	fracval 33034	Value of the field of fractions. (Contributed by Thierry Arnoux, 5-May-2025.)
⊢ ( Frac ‘𝑅) = (𝑅 RLocal (RLReg‘𝑅))
Theorem	fracbas 33035	The base of the field of fractions. (Contributed by Thierry Arnoux, 10-May-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 𝐸 = (RLReg‘𝑅)    &   ⊢ 𝐹 = ( Frac ‘𝑅)    &   ⊢ ∼ = (𝑅 ~RL 𝐸)    ⇒   ⊢ ((𝐵 × 𝐸) / ∼ ) = (Base‘𝐹)
Theorem	fracerl 33036	Rewrite the ring localization equivalence relation in the case of a field of fractions. (Contributed by Thierry Arnoux, 5-May-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ ∼ = (𝑅 ~RL (RLReg‘𝑅))    &   ⊢ (𝜑 → 𝑅 ∈ CRing)    &   ⊢ (𝜑 → 𝐸 ∈ 𝐵)    &   ⊢ (𝜑 → 𝐺 ∈ 𝐵)    &   ⊢ (𝜑 → 𝐹 ∈ (RLReg‘𝑅))    &   ⊢ (𝜑 → 𝐻 ∈ (RLReg‘𝑅))    ⇒   ⊢ (𝜑 → (⟨𝐸, 𝐹⟩ ∼ ⟨𝐺, 𝐻⟩ ↔ (𝐸 · 𝐻) = (𝐺 · 𝐹)))
Theorem	fracf1 33037*	The embedding of a commutative ring 𝑅 into its field of fractions. (Contributed by Thierry Arnoux, 10-May-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 𝐸 = (RLReg‘𝑅)    &   ⊢ 1 = (1r‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ CRing)    &   ⊢ ∼ = (𝑅 ~RL 𝐸)    &   ⊢ 𝐹 = (𝑥 ∈ 𝐵 ↦ [⟨𝑥, 1 ⟩] ∼ )    ⇒   ⊢ (𝜑 → (𝐹:𝐵–1-1→((𝐵 × 𝐸) / ∼ ) ∧ 𝐹 ∈ (𝑅 RingHom ( Frac ‘𝑅))))
Theorem	fracfld 33038	The field of fractions of an integral domain is a field. (Contributed by Thierry Arnoux, 4-May-2025.)
⊢ (𝜑 → 𝑅 ∈ IDomn)    ⇒   ⊢ (𝜑 → ( Frac ‘𝑅) ∈ Field)
Theorem	idomsubr 33039*	Every integral domain is isomorphic with a subring of some field. (Proposed by Gerard Lang, 10-May-2025.) (Contributed by Thierry Arnoux, 10-May-2025.)
⊢ (𝜑 → 𝑅 ∈ IDomn)    ⇒   ⊢ (𝜑 → ∃𝑓 ∈ Field ∃𝑠 ∈ (SubRing‘𝑓)𝑅 ≃𝑟 (𝑓 ↾s 𝑠))
21.3.9.23  Field extensions generated by a set
Syntax	cfldgen 33040	Syntax for a function generating sub-fields.
class fldGen
Definition	df-fldgen 33041*	Define a function generating the smallest sub-division-ring of a given ring containing a given set. If the base structure is a division ring, then this is also a division ring (see fldgensdrg 33044). If the base structure is a field, this is a subfield (see fldgenfld 33050 and fldsdrgfld 20685). In general this will be used in the context of fields, hence the name fldGen. (Contributed by Saveliy Skresanov and Thierry Arnoux, 9-Jan-2025.)
⊢ fldGen = (𝑓 ∈ V, 𝑠 ∈ V ↦ ∩ {𝑎 ∈ (SubDRing‘𝑓) ∣ 𝑠 ⊆ 𝑎})
Theorem	fldgenval 33042*	Value of the field generating function: (𝐹 fldGen 𝑆) is the smallest sub-division-ring of 𝐹 containing 𝑆. (Contributed by Thierry Arnoux, 11-Jan-2025.)
⊢ 𝐵 = (Base‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ DivRing)    &   ⊢ (𝜑 → 𝑆 ⊆ 𝐵)    ⇒   ⊢ (𝜑 → (𝐹 fldGen 𝑆) = ∩ {𝑎 ∈ (SubDRing‘𝐹) ∣ 𝑆 ⊆ 𝑎})
Theorem	fldgenssid 33043	The field generated by a set of elements contains those elements. See lspssid 20868. (Contributed by Thierry Arnoux, 15-Jan-2025.)
⊢ 𝐵 = (Base‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ DivRing)    &   ⊢ (𝜑 → 𝑆 ⊆ 𝐵)    ⇒   ⊢ (𝜑 → 𝑆 ⊆ (𝐹 fldGen 𝑆))
Theorem	fldgensdrg 33044	A generated subfield is a sub-division-ring. (Contributed by Thierry Arnoux, 11-Jan-2025.)
⊢ 𝐵 = (Base‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ DivRing)    &   ⊢ (𝜑 → 𝑆 ⊆ 𝐵)    ⇒   ⊢ (𝜑 → (𝐹 fldGen 𝑆) ∈ (SubDRing‘𝐹))
Theorem	fldgenssv 33045	A generated subfield is a subset of the field's base. (Contributed by Thierry Arnoux, 25-Feb-2025.)
⊢ 𝐵 = (Base‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ DivRing)    &   ⊢ (𝜑 → 𝑆 ⊆ 𝐵)    ⇒   ⊢ (𝜑 → (𝐹 fldGen 𝑆) ⊆ 𝐵)
Theorem	fldgenss 33046	Generated subfields preserve subset ordering. ( see lspss 20867 and spanss 31197) (Contributed by Thierry Arnoux, 15-Jan-2025.)
⊢ 𝐵 = (Base‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ DivRing)    &   ⊢ (𝜑 → 𝑆 ⊆ 𝐵)    &   ⊢ (𝜑 → 𝑇 ⊆ 𝑆)    ⇒   ⊢ (𝜑 → (𝐹 fldGen 𝑇) ⊆ (𝐹 fldGen 𝑆))
Theorem	fldgenidfld 33047	The subfield generated by a subfield is the subfield itself. (Contributed by Thierry Arnoux, 15-Jan-2025.)
⊢ 𝐵 = (Base‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ DivRing)    &   ⊢ (𝜑 → 𝑆 ∈ (SubDRing‘𝐹))    ⇒   ⊢ (𝜑 → (𝐹 fldGen 𝑆) = 𝑆)
Theorem	fldgenssp 33048	The field generated by a set of elements in a division ring is contained in any sub-division-ring which contains those elements. (Contributed by Thierry Arnoux, 25-Feb-2025.)
⊢ 𝐵 = (Base‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ DivRing)    &   ⊢ (𝜑 → 𝑆 ∈ (SubDRing‘𝐹))    &   ⊢ (𝜑 → 𝑇 ⊆ 𝑆)    ⇒   ⊢ (𝜑 → (𝐹 fldGen 𝑇) ⊆ 𝑆)
Theorem	fldgenid 33049	The subfield of a field 𝐹 generated by the whole base set of 𝐹 is 𝐹 itself. (Contributed by Thierry Arnoux, 11-Jan-2025.)
⊢ 𝐵 = (Base‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ DivRing)    ⇒   ⊢ (𝜑 → (𝐹 fldGen 𝐵) = 𝐵)
Theorem	fldgenfld 33050	A generated subfield is a field. (Contributed by Thierry Arnoux, 11-Jan-2025.)
⊢ 𝐵 = (Base‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ Field)    &   ⊢ (𝜑 → 𝑆 ⊆ 𝐵)    ⇒   ⊢ (𝜑 → (𝐹 ↾s (𝐹 fldGen 𝑆)) ∈ Field)
Theorem	primefldgen1 33051	The prime field of a division ring is the subfield generated by the multiplicative identity element. In general, we should write "prime division ring", but since most later usages are in the case where the ambient ring is commutative, we keep the term "prime field". (Contributed by Thierry Arnoux, 11-Jan-2025.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 1 = (1r‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ DivRing)    ⇒   ⊢ (𝜑 → ∩ (SubDRing‘𝑅) = (𝑅 fldGen { 1 }))
Theorem	1fldgenq 33052	The field of rational numbers ℚ is generated by 1 in ℂfld, that is, ℚ is the prime field of ℂfld. (Contributed by Thierry Arnoux, 15-Jan-2025.)
⊢ (ℂfld fldGen {1}) = ℚ
21.3.9.24  Totally ordered rings and fields
Syntax	corng 33053	Extend class notation with the class of all ordered rings.
class oRing
Syntax	cofld 33054	Extend class notation with the class of all ordered fields.
class oField
Definition	df-orng 33055*	Define class of all ordered rings. An ordered ring is a ring with a total ordering compatible with its operations. (Contributed by Thierry Arnoux, 23-Mar-2018.)
⊢ oRing = {𝑟 ∈ (Ring ∩ oGrp) ∣ [(Base‘𝑟) / 𝑣][(0g‘𝑟) / 𝑧][(.r‘𝑟) / 𝑡][(le‘𝑟) / 𝑙]∀𝑎 ∈ 𝑣 ∀𝑏 ∈ 𝑣 ((𝑧𝑙𝑎 ∧ 𝑧𝑙𝑏) → 𝑧𝑙(𝑎𝑡𝑏))}
Definition	df-ofld 33056	Define class of all ordered fields. An ordered field is a field with a total ordering compatible with its operations. (Contributed by Thierry Arnoux, 18-Jan-2018.)
⊢ oField = (Field ∩ oRing)
Theorem	isorng 33057*	An ordered ring is a ring with a total ordering compatible with its operations. (Contributed by Thierry Arnoux, 18-Jan-2018.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ ≤ = (le‘𝑅)    ⇒   ⊢ (𝑅 ∈ oRing ↔ (𝑅 ∈ Ring ∧ 𝑅 ∈ oGrp ∧ ∀𝑎 ∈ 𝐵 ∀𝑏 ∈ 𝐵 (( 0 ≤ 𝑎 ∧ 0 ≤ 𝑏) → 0 ≤ (𝑎 · 𝑏))))
Theorem	orngring 33058	An ordered ring is a ring. (Contributed by Thierry Arnoux, 23-Mar-2018.)
⊢ (𝑅 ∈ oRing → 𝑅 ∈ Ring)
Theorem	orngogrp 33059	An ordered ring is an ordered group. (Contributed by Thierry Arnoux, 23-Mar-2018.)
⊢ (𝑅 ∈ oRing → 𝑅 ∈ oGrp)
Theorem	isofld 33060	An ordered field is a field with a total ordering compatible with its operations. (Contributed by Thierry Arnoux, 23-Mar-2018.)
⊢ (𝐹 ∈ oField ↔ (𝐹 ∈ Field ∧ 𝐹 ∈ oRing))
Theorem	orngmul 33061	In an ordered ring, the ordering is compatible with the ring multiplication operation. (Contributed by Thierry Arnoux, 20-Jan-2018.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ ≤ = (le‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ · = (.r‘𝑅)    ⇒   ⊢ ((𝑅 ∈ oRing ∧ (𝑋 ∈ 𝐵 ∧ 0 ≤ 𝑋) ∧ (𝑌 ∈ 𝐵 ∧ 0 ≤ 𝑌)) → 0 ≤ (𝑋 · 𝑌))
Theorem	orngsqr 33062	In an ordered ring, all squares are positive. (Contributed by Thierry Arnoux, 20-Jan-2018.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ ≤ = (le‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ · = (.r‘𝑅)    ⇒   ⊢ ((𝑅 ∈ oRing ∧ 𝑋 ∈ 𝐵) → 0 ≤ (𝑋 · 𝑋))
Theorem	ornglmulle 33063	In an ordered ring, multiplication with a positive does not change comparison. (Contributed by Thierry Arnoux, 10-Apr-2018.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ oRing)    &   ⊢ (𝜑 → 𝑋 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑌 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑍 ∈ 𝐵)    &   ⊢ ≤ = (le‘𝑅)    &   ⊢ (𝜑 → 𝑋 ≤ 𝑌)    &   ⊢ (𝜑 → 0 ≤ 𝑍)    ⇒   ⊢ (𝜑 → (𝑍 · 𝑋) ≤ (𝑍 · 𝑌))
Theorem	orngrmulle 33064	In an ordered ring, multiplication with a positive does not change comparison. (Contributed by Thierry Arnoux, 10-Apr-2018.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ oRing)    &   ⊢ (𝜑 → 𝑋 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑌 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑍 ∈ 𝐵)    &   ⊢ ≤ = (le‘𝑅)    &   ⊢ (𝜑 → 𝑋 ≤ 𝑌)    &   ⊢ (𝜑 → 0 ≤ 𝑍)    ⇒   ⊢ (𝜑 → (𝑋 · 𝑍) ≤ (𝑌 · 𝑍))
Theorem	ornglmullt 33065	In an ordered ring, multiplication with a positive does not change strict comparison. (Contributed by Thierry Arnoux, 9-Apr-2018.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ oRing)    &   ⊢ (𝜑 → 𝑋 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑌 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑍 ∈ 𝐵)    &   ⊢ < = (lt‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ DivRing)    &   ⊢ (𝜑 → 𝑋 < 𝑌)    &   ⊢ (𝜑 → 0 < 𝑍)    ⇒   ⊢ (𝜑 → (𝑍 · 𝑋) < (𝑍 · 𝑌))
Theorem	orngrmullt 33066	In an ordered ring, multiplication with a positive does not change strict comparison. (Contributed by Thierry Arnoux, 9-Apr-2018.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ oRing)    &   ⊢ (𝜑 → 𝑋 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑌 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑍 ∈ 𝐵)    &   ⊢ < = (lt‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ DivRing)    &   ⊢ (𝜑 → 𝑋 < 𝑌)    &   ⊢ (𝜑 → 0 < 𝑍)    ⇒   ⊢ (𝜑 → (𝑋 · 𝑍) < (𝑌 · 𝑍))
Theorem	orngmullt 33067	In an ordered ring, the strict ordering is compatible with the ring multiplication operation. (Contributed by Thierry Arnoux, 9-Sep-2018.)
⊢ 𝐵 = (Base‘𝑅)    &   ⊢ · = (.r‘𝑅)    &   ⊢ 0 = (0g‘𝑅)    &   ⊢ < = (lt‘𝑅)    &   ⊢ (𝜑 → 𝑅 ∈ oRing)    &   ⊢ (𝜑 → 𝑅 ∈ DivRing)    &   ⊢ (𝜑 → 𝑋 ∈ 𝐵)    &   ⊢ (𝜑 → 𝑌 ∈ 𝐵)    &   ⊢ (𝜑 → 0 < 𝑋)    &   ⊢ (𝜑 → 0 < 𝑌)    ⇒   ⊢ (𝜑 → 0 < (𝑋 · 𝑌))
Theorem	ofldfld 33068	An ordered field is a field. (Contributed by Thierry Arnoux, 20-Jan-2018.)
⊢ (𝐹 ∈ oField → 𝐹 ∈ Field)
Theorem	ofldtos 33069	An ordered field is a totally ordered set. (Contributed by Thierry Arnoux, 20-Jan-2018.)
⊢ (𝐹 ∈ oField → 𝐹 ∈ Toset)
Theorem	orng0le1 33070	In an ordered ring, the ring unity is positive. (Contributed by Thierry Arnoux, 21-Jan-2018.)
⊢ 0 = (0g‘𝐹)    &   ⊢ 1 = (1r‘𝐹)    &   ⊢ ≤ = (le‘𝐹)    ⇒   ⊢ (𝐹 ∈ oRing → 0 ≤ 1 )
Theorem	ofldlt1 33071	In an ordered field, the ring unity is strictly positive. (Contributed by Thierry Arnoux, 21-Jan-2018.)
⊢ 0 = (0g‘𝐹)    &   ⊢ 1 = (1r‘𝐹)    &   ⊢ < = (lt‘𝐹)    ⇒   ⊢ (𝐹 ∈ oField → 0 < 1 )
Theorem	ofldchr 33072	The characteristic of an ordered field is zero. (Contributed by Thierry Arnoux, 21-Jan-2018.) (Proof shortened by AV, 6-Oct-2020.)
⊢ (𝐹 ∈ oField → (chr‘𝐹) = 0)
Theorem	suborng 33073	Every subring of an ordered ring is also an ordered ring. (Contributed by Thierry Arnoux, 21-Jan-2018.)
⊢ ((𝑅 ∈ oRing ∧ (𝑅 ↾s 𝐴) ∈ Ring) → (𝑅 ↾s 𝐴) ∈ oRing)
Theorem	subofld 33074	Every subfield of an ordered field is also an ordered field. (Contributed by Thierry Arnoux, 21-Jan-2018.)
⊢ ((𝐹 ∈ oField ∧ (𝐹 ↾s 𝐴) ∈ Field) → (𝐹 ↾s 𝐴) ∈ oField)
Theorem	isarchiofld 33075*	Axiom of Archimedes : a characterization of the Archimedean property for ordered fields. (Contributed by Thierry Arnoux, 9-Apr-2018.)
⊢ 𝐵 = (Base‘𝑊)    &   ⊢ 𝐻 = (ℤRHom‘𝑊)    &   ⊢ < = (lt‘𝑊)    ⇒   ⊢ (𝑊 ∈ oField → (𝑊 ∈ Archi ↔ ∀𝑥 ∈ 𝐵 ∃𝑛 ∈ ℕ 𝑥 < (𝐻‘𝑛)))
21.3.9.25  Ring homomorphisms - misc additions
Theorem	rhmdvd 33076	A ring homomorphism preserves ratios. (Contributed by Thierry Arnoux, 22-Oct-2017.)
⊢ 𝑈 = (Unit‘𝑆)    &   ⊢ 𝑋 = (Base‘𝑅)    &   ⊢ / = (/r‘𝑆)    &   ⊢ · = (.r‘𝑅)    ⇒   ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ (𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋 ∧ 𝐶 ∈ 𝑋) ∧ ((𝐹‘𝐵) ∈ 𝑈 ∧ (𝐹‘𝐶) ∈ 𝑈)) → ((𝐹‘𝐴) / (𝐹‘𝐵)) = ((𝐹‘(𝐴 · 𝐶)) / (𝐹‘(𝐵 · 𝐶))))
Theorem	kerunit 33077	If a unit element lies in the kernel of a ring homomorphism, then 0 = 1, i.e. the target ring is the zero ring. (Contributed by Thierry Arnoux, 24-Oct-2017.)
⊢ 𝑈 = (Unit‘𝑅)    &   ⊢ 0 = (0g‘𝑆)    &   ⊢ 1 = (1r‘𝑆)    ⇒   ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ (𝑈 ∩ (◡𝐹 “ { 0 })) ≠ ∅) → 1 = 0 )
21.3.9.26  Scalar restriction operation
Syntax	cresv 33078	Extend class notation with the scalar restriction operation.
class ↾v
Definition	df-resv 33079*	Define an operator to restrict the scalar field component of an extended structure. (Contributed by Thierry Arnoux, 5-Sep-2018.)
⊢ ↾v = (𝑤 ∈ V, 𝑥 ∈ V ↦ if((Base‘(Scalar‘𝑤)) ⊆ 𝑥, 𝑤, (𝑤 sSet ⟨(Scalar‘ndx), ((Scalar‘𝑤) ↾s 𝑥)⟩)))
Theorem	reldmresv 33080	The scalar restriction is a proper operator, so it can be used with ovprc1 7452. (Contributed by Thierry Arnoux, 6-Sep-2018.)
⊢ Rel dom ↾v
Theorem	resvval 33081	Value of structure restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.)
⊢ 𝑅 = (𝑊 ↾v 𝐴)    &   ⊢ 𝐹 = (Scalar‘𝑊)    &   ⊢ 𝐵 = (Base‘𝐹)    ⇒   ⊢ ((𝑊 ∈ 𝑋 ∧ 𝐴 ∈ 𝑌) → 𝑅 = if(𝐵 ⊆ 𝐴, 𝑊, (𝑊 sSet ⟨(Scalar‘ndx), (𝐹 ↾s 𝐴)⟩)))
Theorem	resvid2 33082	General behavior of trivial restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.)
⊢ 𝑅 = (𝑊 ↾v 𝐴)    &   ⊢ 𝐹 = (Scalar‘𝑊)    &   ⊢ 𝐵 = (Base‘𝐹)    ⇒   ⊢ ((𝐵 ⊆ 𝐴 ∧ 𝑊 ∈ 𝑋 ∧ 𝐴 ∈ 𝑌) → 𝑅 = 𝑊)
Theorem	resvval2 33083	Value of nontrivial structure restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.)
⊢ 𝑅 = (𝑊 ↾v 𝐴)    &   ⊢ 𝐹 = (Scalar‘𝑊)    &   ⊢ 𝐵 = (Base‘𝐹)    ⇒   ⊢ ((¬ 𝐵 ⊆ 𝐴 ∧ 𝑊 ∈ 𝑋 ∧ 𝐴 ∈ 𝑌) → 𝑅 = (𝑊 sSet ⟨(Scalar‘ndx), (𝐹 ↾s 𝐴)⟩))
Theorem	resvsca 33084	Base set of a structure restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.)
⊢ 𝑅 = (𝑊 ↾v 𝐴)    &   ⊢ 𝐹 = (Scalar‘𝑊)    &   ⊢ 𝐵 = (Base‘𝐹)    ⇒   ⊢ (𝐴 ∈ 𝑉 → (𝐹 ↾s 𝐴) = (Scalar‘𝑅))
Theorem	resvlem 33085	Other elements of a scalar restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.) (Revised by AV, 31-Oct-2024.)
⊢ 𝑅 = (𝑊 ↾v 𝐴)    &   ⊢ 𝐶 = (𝐸‘𝑊)    &   ⊢ 𝐸 = Slot (𝐸‘ndx)    &   ⊢ (𝐸‘ndx) ≠ (Scalar‘ndx)    ⇒   ⊢ (𝐴 ∈ 𝑉 → 𝐶 = (𝐸‘𝑅))
Theorem	resvlemOLD 33086	Obsolete version of resvlem 33085 as of 31-Oct-2024. Other elements of a structure restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.) (New usage is discouraged.) (Proof modification is discouraged.)
⊢ 𝑅 = (𝑊 ↾v 𝐴)    &   ⊢ 𝐶 = (𝐸‘𝑊)    &   ⊢ 𝐸 = Slot 𝑁    &   ⊢ 𝑁 ∈ ℕ    &   ⊢ 𝑁 ≠ 5    ⇒   ⊢ (𝐴 ∈ 𝑉 → 𝐶 = (𝐸‘𝑅))
Theorem	resvbas 33087	Base is unaffected by scalar restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.) (Revised by AV, 31-Oct-2024.)
⊢ 𝐻 = (𝐺 ↾v 𝐴)    &   ⊢ 𝐵 = (Base‘𝐺)    ⇒   ⊢ (𝐴 ∈ 𝑉 → 𝐵 = (Base‘𝐻))
Theorem	resvbasOLD 33088	Obsolete proof of resvbas 33087 as of 31-Oct-2024. Base is unaffected by scalar restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.) (New usage is discouraged.) (Proof modification is discouraged.)
⊢ 𝐻 = (𝐺 ↾v 𝐴)    &   ⊢ 𝐵 = (Base‘𝐺)    ⇒   ⊢ (𝐴 ∈ 𝑉 → 𝐵 = (Base‘𝐻))
Theorem	resvplusg 33089	+g is unaffected by scalar restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.) (Revised by AV, 31-Oct-2024.)
⊢ 𝐻 = (𝐺 ↾v 𝐴)    &   ⊢ + = (+g‘𝐺)    ⇒   ⊢ (𝐴 ∈ 𝑉 → + = (+g‘𝐻))
Theorem	resvplusgOLD 33090	Obsolete proof of resvplusg 33089 as of 31-Oct-2024. +g is unaffected by scalar restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.) (New usage is discouraged.) (Proof modification is discouraged.)
⊢ 𝐻 = (𝐺 ↾v 𝐴)    &   ⊢ + = (+g‘𝐺)    ⇒   ⊢ (𝐴 ∈ 𝑉 → + = (+g‘𝐻))
Theorem	resvvsca 33091	·𝑠 is unaffected by scalar restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.) (Proof shortened by AV, 31-Oct-2024.)
⊢ 𝐻 = (𝐺 ↾v 𝐴)    &   ⊢ · = ( ·𝑠 ‘𝐺)    ⇒   ⊢ (𝐴 ∈ 𝑉 → · = ( ·𝑠 ‘𝐻))
Theorem	resvvscaOLD 33092	Obsolete proof of resvvsca 33091 as of 31-Oct-2024. ·𝑠 is unaffected by scalar restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.) (New usage is discouraged.) (Proof modification is discouraged.)
⊢ 𝐻 = (𝐺 ↾v 𝐴)    &   ⊢ · = ( ·𝑠 ‘𝐺)    ⇒   ⊢ (𝐴 ∈ 𝑉 → · = ( ·𝑠 ‘𝐻))
Theorem	resvmulr 33093	.r is unaffected by scalar restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.) (Revised by AV, 31-Oct-2024.)
⊢ 𝐻 = (𝐺 ↾v 𝐴)    &   ⊢ · = (.r‘𝐺)    ⇒   ⊢ (𝐴 ∈ 𝑉 → · = (.r‘𝐻))
Theorem	resvmulrOLD 33094	Obsolete proof of resvmulr 33093 as of 31-Oct-2024. ·𝑠 is unaffected by scalar restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.) (New usage is discouraged.) (Proof modification is discouraged.)
⊢ 𝐻 = (𝐺 ↾v 𝐴)    &   ⊢ · = (.r‘𝐺)    ⇒   ⊢ (𝐴 ∈ 𝑉 → · = (.r‘𝐻))
Theorem	resv0g 33095	0g is unaffected by scalar restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.)
⊢ 𝐻 = (𝐺 ↾v 𝐴)    &   ⊢ 0 = (0g‘𝐺)    ⇒   ⊢ (𝐴 ∈ 𝑉 → 0 = (0g‘𝐻))
Theorem	resv1r 33096	1r is unaffected by scalar restriction. (Contributed by Thierry Arnoux, 6-Sep-2018.)
⊢ 𝐻 = (𝐺 ↾v 𝐴)    &   ⊢ 1 = (1r‘𝐺)    ⇒   ⊢ (𝐴 ∈ 𝑉 → 1 = (1r‘𝐻))
Theorem	resvcmn 33097	Scalar restriction preserves commutative monoids. (Contributed by Thierry Arnoux, 6-Sep-2018.)
⊢ 𝐻 = (𝐺 ↾v 𝐴)    ⇒   ⊢ (𝐴 ∈ 𝑉 → (𝐺 ∈ CMnd ↔ 𝐻 ∈ CMnd))
21.3.9.27  The commutative ring of gaussian integers
Theorem	gzcrng 33098	The gaussian integers form a commutative ring. (Contributed by Thierry Arnoux, 18-Mar-2018.)
⊢ (ℂfld ↾s ℤ[i]) ∈ CRing
21.3.9.28  The archimedean ordered field of real numbers
Theorem	reofld 33099	The real numbers form an ordered field. (Contributed by Thierry Arnoux, 21-Jan-2018.)
⊢ ℝfld ∈ oField
Theorem	nn0omnd 33100	The nonnegative integers form an ordered monoid. (Contributed by Thierry Arnoux, 23-Mar-2018.)
⊢ (ℂfld ↾s ℕ0) ∈ oMnd