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Type | Label | Description |
---|---|---|
Statement | ||
Theorem | ex-1st 27301 | Example for df-1st 7168. Example by David A. Wheeler. (Contributed by Mario Carneiro, 18-Jun-2015.) |
⊢ (1st ‘〈3, 4〉) = 3 | ||
Theorem | ex-2nd 27302 | Example for df-2nd 7169. Example by David A. Wheeler. (Contributed by Mario Carneiro, 18-Jun-2015.) |
⊢ (2nd ‘〈3, 4〉) = 4 | ||
Theorem | 1kp2ke3k 27303 |
Example for df-dec 11494, 1000 + 2000 = 3000.
This proof disproves (by counterexample) the assertion of Hao Wang, who stated, "There is a theorem in the primitive notation of set theory that corresponds to the arithmetic theorem 1000 + 2000 = 3000. The formula would be forbiddingly long... even if (one) knows the definitions and is asked to simplify the long formula according to them, chances are he will make errors and arrive at some incorrect result." (Hao Wang, "Theory and practice in mathematics" , In Thomas Tymoczko, editor, New Directions in the Philosophy of Mathematics, pp 129-152, Birkauser Boston, Inc., Boston, 1986. (QA8.6.N48). The quote itself is on page 140.) This is noted in Metamath: A Computer Language for Pure Mathematics by Norman Megill (2007) section 1.1.3. Megill then states, "A number of writers have conveyed the impression that the kind of absolute rigor provided by Metamath is an impossible dream, suggesting that a complete, formal verification of a typical theorem would take millions of steps in untold volumes of books... These writers assume, however, that in order to achieve the kind of complete formal verification they desire one must break down a proof into individual primitive steps that make direct reference to the axioms. This is not necessary. There is no reason not to make use of previously proved theorems rather than proving them over and over... A hierarchy of theorems and definitions permits an exponential growth in the formula sizes and primitive proof steps to be described with only a linear growth in the number of symbols used. Of course, this is how ordinary informal mathematics is normally done anyway, but with Metamath it can be done with absolute rigor and precision." The proof here starts with (2 + 1) = 3, commutes it, and repeatedly multiplies both sides by ten. This is certainly longer than traditional mathematical proofs, e.g., there are a number of steps explicitly shown here to show that we're allowed to do operations such as multiplication. However, while longer, the proof is clearly a manageable size - even though every step is rigorously derived all the way back to the primitive notions of set theory and logic. And while there's a risk of making errors, the many independent verifiers make it much less likely that an incorrect result will be accepted. This proof heavily relies on the decimal constructor df-dec 11494 developed by Mario Carneiro in 2015. The underlying Metamath language has an intentionally very small set of primitives; it doesn't even have a built-in construct for numbers. Instead, the digits are defined using these primitives, and the decimal constructor is used to make it easy to express larger numbers as combinations of digits. (Contributed by David A. Wheeler, 29-Jun-2016.) (Shortened by Mario Carneiro using the arithmetic algorithm in mmj2, 30-Jun-2016.) |
⊢ (;;;1000 + ;;;2000) = ;;;3000 | ||
Theorem | ex-fl 27304 | Example for df-fl 12593. Example by David A. Wheeler. (Contributed by Mario Carneiro, 18-Jun-2015.) |
⊢ ((⌊‘(3 / 2)) = 1 ∧ (⌊‘-(3 / 2)) = -2) | ||
Theorem | ex-ceil 27305 | Example for df-ceil 12594. (Contributed by AV, 4-Sep-2021.) |
⊢ ((⌈‘(3 / 2)) = 2 ∧ (⌈‘-(3 / 2)) = -1) | ||
Theorem | ex-mod 27306 | Example for df-mod 12669. (Contributed by AV, 3-Sep-2021.) |
⊢ ((5 mod 3) = 2 ∧ (-7 mod 2) = 1) | ||
Theorem | ex-exp 27307 | Example for df-exp 12861. (Contributed by AV, 4-Sep-2021.) |
⊢ ((5↑2) = ;25 ∧ (-3↑-2) = (1 / 9)) | ||
Theorem | ex-fac 27308 | Example for df-fac 13061. (Contributed by AV, 4-Sep-2021.) |
⊢ (!‘5) = ;;120 | ||
Theorem | ex-bc 27309 | Example for df-bc 13090. (Contributed by AV, 4-Sep-2021.) |
⊢ (5C3) = ;10 | ||
Theorem | ex-hash 27310 | Example for df-hash 13118. (Contributed by AV, 4-Sep-2021.) |
⊢ (#‘{0, 1, 2}) = 3 | ||
Theorem | ex-sqrt 27311 | Example for df-sqrt 13975. (Contributed by AV, 4-Sep-2021.) |
⊢ (√‘;25) = 5 | ||
Theorem | ex-abs 27312 | Example for df-abs 13976. (Contributed by AV, 4-Sep-2021.) |
⊢ (abs‘-2) = 2 | ||
Theorem | ex-dvds 27313 | Example for df-dvds 14984: 3 divides into 6. (Contributed by David A. Wheeler, 19-May-2015.) |
⊢ 3 ∥ 6 | ||
Theorem | ex-gcd 27314 | Example for df-gcd 15217. (Contributed by AV, 5-Sep-2021.) |
⊢ (-6 gcd 9) = 3 | ||
Theorem | ex-lcm 27315 | Example for df-lcm 15303. (Contributed by AV, 5-Sep-2021.) |
⊢ (6 lcm 9) = ;18 | ||
Theorem | ex-prmo 27316 | Example for df-prmo 15736: (#p‘10) = 2 · 3 · 5 · 7. (Contributed by AV, 6-Sep-2021.) |
⊢ (#p‘;10) = ;;210 | ||
Theorem | aevdemo 27317* | Proof illustrating the comment of aev2 1986. (Contributed by BJ, 30-Mar-2021.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (∀𝑥 𝑥 = 𝑦 → ((∃𝑎∀𝑏 𝑐 = 𝑑 ∨ ∃𝑒 𝑓 = 𝑔) ∧ ∀ℎ(𝑖 = 𝑗 → 𝑘 = 𝑙))) | ||
Theorem | ex-ind-dvds 27318 | Example of a proof by induction (divisibility result). (Contributed by Stanislas Polu, 9-Mar-2020.) (Revised by BJ, 24-Mar-2020.) |
⊢ (𝑁 ∈ ℕ0 → 3 ∥ ((4↑𝑁) + 2)) | ||
Theorem | avril1 27319 |
Poisson d'Avril's Theorem. This theorem is noted for its
Selbstdokumentieren property, which means, literally,
"self-documenting" and recalls the principle of quidquid
german dictum
sit, altum viditur, often used in set theory. Starting with the
seemingly simple yet profound fact that any object 𝑥 equals
itself
(proved by Tarski in 1965; see Lemma 6 of [Tarski] p. 68), we
demonstrate that the power set of the real numbers, as a relation on the
value of the imaginary unit, does not conjoin with an empty relation on
the product of the additive and multiplicative identity elements,
leading to this startling conclusion that has left even seasoned
professional mathematicians scratching their heads. (Contributed by
Prof. Loof Lirpa, 1-Apr-2005.) (Proof modification is discouraged.)
(New usage is discouraged.)
A reply to skeptics can be found at mmnotes.txt, under the 1-Apr-2006 entry. |
⊢ ¬ (𝐴𝒫 ℝ(i‘1) ∧ 𝐹∅(0 · 1)) | ||
Theorem | 2bornot2b 27320 | The law of excluded middle. Act III, Theorem 1 of Shakespeare, Hamlet, Prince of Denmark (1602). Its author leaves its proof as an exercise for the reader - "To be, or not to be: that is the question" - starting a trend that has become standard in modern-day textbooks, serving to make the frustrated reader feel inferior, or in some cases to mask the fact that the author does not know its solution. (Contributed by Prof. Loof Lirpa, 1-Apr-2006.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (2 · 𝐵 ∨ ¬ 2 · 𝐵) | ||
Theorem | helloworld 27321 | The classic "Hello world" benchmark has been translated into 314 computer programming languages - see http://www.roesler-ac.de/wolfram/hello.htm. However, for many years it eluded a proof that it is more than just a conjecture, even though a wily mathematician once claimed, "I have discovered a truly marvelous proof of this, which this margin is too narrow to contain." Using an IBM 709 mainframe, a team of mathematicians led by Prof. Loof Lirpa, at the New College of Tahiti, were finally able put it rest with a remarkably short proof only 4 lines long. (Contributed by Prof. Loof Lirpa, 1-Apr-2007.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ ¬ (ℎ ∈ (𝐿𝐿0) ∧ 𝑊∅(R1𝑑)) | ||
Theorem | 1p1e2apr1 27322 | One plus one equals two. Using proof-shortening techniques pioneered by Mr. Mel L. O'Cat, along with the latest supercomputer technology, Prof. Loof Lirpa and colleagues were able to shorten Whitehead and Russell's 360-page proof that 1+1=2 in Principia Mathematica to this remarkable proof only two steps long, thus establishing a new world's record for this famous theorem. (Contributed by Prof. Loof Lirpa, 1-Apr-2008.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (1 + 1) = 2 | ||
Theorem | eqid1 27323 |
Law of identity (reflexivity of class equality). Theorem 6.4 of [Quine]
p. 41.
This law is thought to have originated with Aristotle (Metaphysics, Book VII, Part 17). It is one of the three axioms of Ayn Rand's philosophy (Atlas Shrugged, Part Three, Chapter VII). While some have proposed extending Rand's axiomatization to include Compassion and Kindness, others fear that such an extension may flirt with logical inconsistency. (Contributed by Stefan Allan, 1-Apr-2009.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ 𝐴 = 𝐴 | ||
Theorem | 1div0apr 27324 | Division by zero is forbidden! If we try, we encounter the DO NOT ENTER sign, which in mathematics means it is foolhardy to venture any further, possibly putting the underlying fabric of reality at risk. Based on a dare by David A. Wheeler. (Contributed by Mario Carneiro, 1-Apr-2014.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (1 / 0) = ∅ | ||
Theorem | topnfbey 27325 | Nothing seems to be impossible to Prof. Lirpa. After years of intensive research, he managed to find a proof that when given a chance to reach infinity, one could indeed go beyond, thus giving formal soundness to Buzz Lightyear's motto "To infinity... and beyond!" (Contributed by Prof. Loof Lirpa, 1-Apr-2020.) (Modified by Thierry Arnoux, 2-Aug-2020.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (𝐵 ∈ (0...+∞) → +∞ < 𝐵) | ||
Syntax | cplig 27326 | Extend class notation with the class of all planar incidence geometries. |
class Plig | ||
Definition | df-plig 27327* |
Define the class of planar incidence geometries. We use Hilbert's
axioms and adapt them to planar geometry. We use ∈ for the
incidence relation. We could have used a generic binary relation, but
using ∈ allows us to reuse previous
results. Much of what follows
is directly borrowed from Aitken, Incidence-Betweenness Geometry,
2008, http://public.csusm.edu/aitken_html/m410/betweenness.08.pdf.
The class Plig is the class of planar incidence geometries, where a planar incidence geometry is defined as a set of lines satisfying three axioms. In the definition below, 𝑥 denotes a planar incidence geometry, so ∪ 𝑥 denotes the union of its lines, that is, the set of points in the plane, 𝑙 denotes a line, and 𝑎, 𝑏, 𝑐 denote points. Therefore, the axioms are: 1) for all pairs of (distinct) points, there exists a unique line containing them; 2) all lines contain at least two points; 3) there exist three non-collinear points. (Contributed by FL, 2-Aug-2009.) |
⊢ Plig = {𝑥 ∣ (∀𝑎 ∈ ∪ 𝑥∀𝑏 ∈ ∪ 𝑥(𝑎 ≠ 𝑏 → ∃!𝑙 ∈ 𝑥 (𝑎 ∈ 𝑙 ∧ 𝑏 ∈ 𝑙)) ∧ ∀𝑙 ∈ 𝑥 ∃𝑎 ∈ ∪ 𝑥∃𝑏 ∈ ∪ 𝑥(𝑎 ≠ 𝑏 ∧ 𝑎 ∈ 𝑙 ∧ 𝑏 ∈ 𝑙) ∧ ∃𝑎 ∈ ∪ 𝑥∃𝑏 ∈ ∪ 𝑥∃𝑐 ∈ ∪ 𝑥∀𝑙 ∈ 𝑥 ¬ (𝑎 ∈ 𝑙 ∧ 𝑏 ∈ 𝑙 ∧ 𝑐 ∈ 𝑙))} | ||
Theorem | isplig 27328* | The predicate "is a planar incidence geometry" for sets. (Contributed by FL, 2-Aug-2009.) |
⊢ 𝑃 = ∪ 𝐺 ⇒ ⊢ (𝐺 ∈ 𝐴 → (𝐺 ∈ Plig ↔ (∀𝑎 ∈ 𝑃 ∀𝑏 ∈ 𝑃 (𝑎 ≠ 𝑏 → ∃!𝑙 ∈ 𝐺 (𝑎 ∈ 𝑙 ∧ 𝑏 ∈ 𝑙)) ∧ ∀𝑙 ∈ 𝐺 ∃𝑎 ∈ 𝑃 ∃𝑏 ∈ 𝑃 (𝑎 ≠ 𝑏 ∧ 𝑎 ∈ 𝑙 ∧ 𝑏 ∈ 𝑙) ∧ ∃𝑎 ∈ 𝑃 ∃𝑏 ∈ 𝑃 ∃𝑐 ∈ 𝑃 ∀𝑙 ∈ 𝐺 ¬ (𝑎 ∈ 𝑙 ∧ 𝑏 ∈ 𝑙 ∧ 𝑐 ∈ 𝑙)))) | ||
Theorem | ispligb 27329* | The predicate "is a planar incidence geometry". (Contributed by BJ, 2-Dec-2021.) |
⊢ 𝑃 = ∪ 𝐺 ⇒ ⊢ (𝐺 ∈ Plig ↔ (𝐺 ∈ V ∧ (∀𝑎 ∈ 𝑃 ∀𝑏 ∈ 𝑃 (𝑎 ≠ 𝑏 → ∃!𝑙 ∈ 𝐺 (𝑎 ∈ 𝑙 ∧ 𝑏 ∈ 𝑙)) ∧ ∀𝑙 ∈ 𝐺 ∃𝑎 ∈ 𝑃 ∃𝑏 ∈ 𝑃 (𝑎 ≠ 𝑏 ∧ 𝑎 ∈ 𝑙 ∧ 𝑏 ∈ 𝑙) ∧ ∃𝑎 ∈ 𝑃 ∃𝑏 ∈ 𝑃 ∃𝑐 ∈ 𝑃 ∀𝑙 ∈ 𝐺 ¬ (𝑎 ∈ 𝑙 ∧ 𝑏 ∈ 𝑙 ∧ 𝑐 ∈ 𝑙)))) | ||
Theorem | tncp 27330* | In any planar incidence geometry, there exist three non-collinear points. (Contributed by FL, 3-Aug-2009.) |
⊢ 𝑃 = ∪ 𝐺 ⇒ ⊢ (𝐺 ∈ Plig → ∃𝑎 ∈ 𝑃 ∃𝑏 ∈ 𝑃 ∃𝑐 ∈ 𝑃 ∀𝑙 ∈ 𝐺 ¬ (𝑎 ∈ 𝑙 ∧ 𝑏 ∈ 𝑙 ∧ 𝑐 ∈ 𝑙)) | ||
Theorem | l2p 27331* | For any line in a planar incidence geometry, there exist two different points on the line. (Contributed by AV, 28-Nov-2021.) |
⊢ 𝑃 = ∪ 𝐺 ⇒ ⊢ ((𝐺 ∈ Plig ∧ 𝐿 ∈ 𝐺) → ∃𝑎 ∈ 𝑃 ∃𝑏 ∈ 𝑃 (𝑎 ≠ 𝑏 ∧ 𝑎 ∈ 𝐿 ∧ 𝑏 ∈ 𝐿)) | ||
Theorem | lpni 27332* | For any line in a planar incidence geometry, there exists a point not on the line. (Contributed by Jeff Hankins, 15-Aug-2009.) |
⊢ 𝑃 = ∪ 𝐺 ⇒ ⊢ ((𝐺 ∈ Plig ∧ 𝐿 ∈ 𝐺) → ∃𝑎 ∈ 𝑃 𝑎 ∉ 𝐿) | ||
Theorem | nsnlplig 27333 | There is no "one-point line" in a planar incidence geometry. (Contributed by BJ, 2-Dec-2021.) (Proof shortened by AV, 5-Dec-2021.) |
⊢ (𝐺 ∈ Plig → ¬ {𝐴} ∈ 𝐺) | ||
Theorem | nsnlpligALT 27334 | Alternate version of nsnlplig 27333 using the predicate ∉ instead of ¬ ∈ and whose proof is shorter. (Contributed by AV, 5-Dec-2021.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (𝐺 ∈ Plig → {𝐴} ∉ 𝐺) | ||
Theorem | n0lplig 27335 | There is no "empty line" in a planar incidence geometry. (Contributed by AV, 28-Nov-2021.) (Proof shortened by BJ, 2-Dec-2021.) |
⊢ (𝐺 ∈ Plig → ¬ ∅ ∈ 𝐺) | ||
Theorem | n0lpligALT 27336 | Alternate version of n0lplig 27335 using the predicate ∉ instead of ¬ ∈ and whose proof bypasses nsnlplig 27333. (Contributed by AV, 28-Nov-2021.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (𝐺 ∈ Plig → ∅ ∉ 𝐺) | ||
Theorem | eulplig 27337* | Through two distinct points of a planar incidence geometry, there is a unique line. (Contributed by BJ, 2-Dec-2021.) |
⊢ 𝑃 = ∪ 𝐺 ⇒ ⊢ ((𝐺 ∈ Plig ∧ ((𝐴 ∈ 𝑃 ∧ 𝐵 ∈ 𝑃) ∧ 𝐴 ≠ 𝐵)) → ∃!𝑙 ∈ 𝐺 (𝐴 ∈ 𝑙 ∧ 𝐵 ∈ 𝑙)) | ||
Theorem | pliguhgr 27338 | Any planar incidence geometry can be regarded as a hypergraph with its points as vertices and its lines as edges. See incistruhgr 25974 for a generalization of this case for arbitrary incidence structures (planar incidence geometries are such incidence structures). (Proposed by Gerard Lang, 24-Nov-2021.) (Contributed by AV, 28-Nov-2021.) |
⊢ (𝐺 ∈ Plig → 〈∪ 𝐺, ( I ↾ 𝐺)〉 ∈ UHGraph ) | ||
Syntax | crpm 27339 | Ring primes. |
class RPrime | ||
Definition | df-rprm 27340* | Define the set of prime elements in a ring. A prime element is a nonzero non-unit that satisfies an equivalent of Euclid's lemma euclemma 15425. (Contributed by Mario Carneiro, 17-Feb-2015.) |
⊢ RPrime = (𝑤 ∈ V ↦ ⦋(Base‘𝑤) / 𝑏⦌{𝑝 ∈ (𝑏 ∖ ((Unit‘𝑤) ∪ {(0g‘𝑤)})) ∣ ∀𝑥 ∈ 𝑏 ∀𝑦 ∈ 𝑏 [(∥r‘𝑤) / 𝑑](𝑝𝑑(𝑥(.r‘𝑤)𝑦) → (𝑝𝑑𝑥 ∨ 𝑝𝑑𝑦))}) | ||
A few aliases that we temporarily keep to prevent broken links. If you land on any of these, please let the originating site and/or us know that the link that made you land here should be changed. | ||
Theorem | dummylink 27341 |
Alias for a1ii 1 that may be referenced in some older works, and
kept
here to prevent broken links.
If you landed here, please let the originating site and/or us know that the link that made you land here should be changed to a link to a1ii 1. (Contributed by NM, 7-Feb-2006.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ 𝜑 & ⊢ 𝜓 ⇒ ⊢ 𝜑 | ||
Theorem | id1 27342 |
Alias for idALT 23 that may be referenced in some older works, and
kept
here to prevent broken links.
If you landed here, please let the originating site and/or us know that the link that made you land here should be changed to a link to idALT 23. (Contributed by NM, 30-Sep-1992.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (𝜑 → 𝜑) | ||
The intent is for this deprecated section to be deleted once its theorems have extensible structure versions (or are not useful). You can make a list of "terminal" theorems (i.e., theorems not referenced by anything else) and for each theorem see if there exists an extensible structure version (or decide it is not useful), and if so, delete it. Then repeat this recursively. One way to search for terminal theorems is to log the output ("open log x.txt") of "show usage WHATEVER" in metamath.exe and search for "(None)". | ||
This section contains an earlier development of groups that was defined before extensible structures were introduced. The intent is for this deprecated section to be deleted once the corresponding definitions and theorems for complex topological vector spaces, which are using them, are revised accordingly. | ||
Syntax | cgr 27343 | Extend class notation with the class of all group operations. |
class GrpOp | ||
Syntax | cgi 27344 | Extend class notation with a function mapping a group operation to the group's identity element. |
class GId | ||
Syntax | cgn 27345 | Extend class notation with a function mapping a group operation to the inverse function for the group. |
class inv | ||
Syntax | cgs 27346 | Extend class notation with a function mapping a group operation to the division (or subtraction) operation for the group. |
class /𝑔 | ||
Definition | df-grpo 27347* | Define the class of all group operations. The base set for a group can be determined from its group operation. Based on the definition in Exercise 28 of [Herstein] p. 54. (Contributed by NM, 10-Oct-2006.) (New usage is discouraged.) |
⊢ GrpOp = {𝑔 ∣ ∃𝑡(𝑔:(𝑡 × 𝑡)⟶𝑡 ∧ ∀𝑥 ∈ 𝑡 ∀𝑦 ∈ 𝑡 ∀𝑧 ∈ 𝑡 ((𝑥𝑔𝑦)𝑔𝑧) = (𝑥𝑔(𝑦𝑔𝑧)) ∧ ∃𝑢 ∈ 𝑡 ∀𝑥 ∈ 𝑡 ((𝑢𝑔𝑥) = 𝑥 ∧ ∃𝑦 ∈ 𝑡 (𝑦𝑔𝑥) = 𝑢))} | ||
Definition | df-gid 27348* | Define a function that maps a group operation to the group's identity element. (Contributed by FL, 5-Feb-2010.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ GId = (𝑔 ∈ V ↦ (℩𝑢 ∈ ran 𝑔∀𝑥 ∈ ran 𝑔((𝑢𝑔𝑥) = 𝑥 ∧ (𝑥𝑔𝑢) = 𝑥))) | ||
Definition | df-ginv 27349* | Define a function that maps a group operation to the group's inverse function. (Contributed by NM, 26-Oct-2006.) (New usage is discouraged.) |
⊢ inv = (𝑔 ∈ GrpOp ↦ (𝑥 ∈ ran 𝑔 ↦ (℩𝑧 ∈ ran 𝑔(𝑧𝑔𝑥) = (GId‘𝑔)))) | ||
Definition | df-gdiv 27350* | Define a function that maps a group operation to the group's division (or subtraction) operation. (Contributed by NM, 15-Feb-2008.) (New usage is discouraged.) |
⊢ /𝑔 = (𝑔 ∈ GrpOp ↦ (𝑥 ∈ ran 𝑔, 𝑦 ∈ ran 𝑔 ↦ (𝑥𝑔((inv‘𝑔)‘𝑦)))) | ||
Theorem | isgrpo 27351* | The predicate "is a group operation." Note that 𝑋 is the base set of the group. (Contributed by NM, 10-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ (𝐺 ∈ 𝐴 → (𝐺 ∈ GrpOp ↔ (𝐺:(𝑋 × 𝑋)⟶𝑋 ∧ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑥𝐺𝑦)𝐺𝑧) = (𝑥𝐺(𝑦𝐺𝑧)) ∧ ∃𝑢 ∈ 𝑋 ∀𝑥 ∈ 𝑋 ((𝑢𝐺𝑥) = 𝑥 ∧ ∃𝑦 ∈ 𝑋 (𝑦𝐺𝑥) = 𝑢)))) | ||
Theorem | isgrpoi 27352* | Properties that determine a group operation. Read 𝑁 as 𝑁(𝑥). (Contributed by NM, 4-Nov-2006.) (New usage is discouraged.) |
⊢ 𝑋 ∈ V & ⊢ 𝐺:(𝑋 × 𝑋)⟶𝑋 & ⊢ ((𝑥 ∈ 𝑋 ∧ 𝑦 ∈ 𝑋 ∧ 𝑧 ∈ 𝑋) → ((𝑥𝐺𝑦)𝐺𝑧) = (𝑥𝐺(𝑦𝐺𝑧))) & ⊢ 𝑈 ∈ 𝑋 & ⊢ (𝑥 ∈ 𝑋 → (𝑈𝐺𝑥) = 𝑥) & ⊢ (𝑥 ∈ 𝑋 → 𝑁 ∈ 𝑋) & ⊢ (𝑥 ∈ 𝑋 → (𝑁𝐺𝑥) = 𝑈) ⇒ ⊢ 𝐺 ∈ GrpOp | ||
Theorem | grpofo 27353 | A group operation maps onto the group's underlying set. (Contributed by NM, 30-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ (𝐺 ∈ GrpOp → 𝐺:(𝑋 × 𝑋)–onto→𝑋) | ||
Theorem | grpocl 27354 | Closure law for a group operation. (Contributed by NM, 10-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (𝐴𝐺𝐵) ∈ 𝑋) | ||
Theorem | grpolidinv 27355* | A group has a left identity element, and every member has a left inverse. (Contributed by NM, 2-Nov-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ (𝐺 ∈ GrpOp → ∃𝑢 ∈ 𝑋 ∀𝑥 ∈ 𝑋 ((𝑢𝐺𝑥) = 𝑥 ∧ ∃𝑦 ∈ 𝑋 (𝑦𝐺𝑥) = 𝑢)) | ||
Theorem | grpon0 27356 | The base set of a group is not empty. (Contributed by Szymon Jaroszewicz, 3-Apr-2007.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ (𝐺 ∈ GrpOp → 𝑋 ≠ ∅) | ||
Theorem | grpoass 27357 | A group operation is associative. (Contributed by NM, 10-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ (𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋 ∧ 𝐶 ∈ 𝑋)) → ((𝐴𝐺𝐵)𝐺𝐶) = (𝐴𝐺(𝐵𝐺𝐶))) | ||
Theorem | grpoidinvlem1 27358 | Lemma for grpoidinv 27362. (Contributed by NM, 10-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ (((𝐺 ∈ GrpOp ∧ (𝑌 ∈ 𝑋 ∧ 𝐴 ∈ 𝑋)) ∧ ((𝑌𝐺𝐴) = 𝑈 ∧ (𝐴𝐺𝐴) = 𝐴)) → (𝑈𝐺𝐴) = 𝑈) | ||
Theorem | grpoidinvlem2 27359 | Lemma for grpoidinv 27362. (Contributed by NM, 10-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ (((𝐺 ∈ GrpOp ∧ (𝑌 ∈ 𝑋 ∧ 𝐴 ∈ 𝑋)) ∧ ((𝑈𝐺𝑌) = 𝑌 ∧ (𝑌𝐺𝐴) = 𝑈)) → ((𝐴𝐺𝑌)𝐺(𝐴𝐺𝑌)) = (𝐴𝐺𝑌)) | ||
Theorem | grpoidinvlem3 27360* | Lemma for grpoidinv 27362. (Contributed by NM, 11-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ (𝜑 ↔ ∀𝑥 ∈ 𝑋 (𝑈𝐺𝑥) = 𝑥) & ⊢ (𝜓 ↔ ∀𝑥 ∈ 𝑋 ∃𝑧 ∈ 𝑋 (𝑧𝐺𝑥) = 𝑈) ⇒ ⊢ ((((𝐺 ∈ GrpOp ∧ 𝑈 ∈ 𝑋) ∧ (𝜑 ∧ 𝜓)) ∧ 𝐴 ∈ 𝑋) → ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝐴) = 𝑈 ∧ (𝐴𝐺𝑦) = 𝑈)) | ||
Theorem | grpoidinvlem4 27361* | Lemma for grpoidinv 27362. (Contributed by NM, 14-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ (((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝐴) = 𝑈 ∧ (𝐴𝐺𝑦) = 𝑈)) → (𝐴𝐺𝑈) = (𝑈𝐺𝐴)) | ||
Theorem | grpoidinv 27362* | A group has a left and right identity element, and every member has a left and right inverse. (Contributed by NM, 14-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ (𝐺 ∈ GrpOp → ∃𝑢 ∈ 𝑋 ∀𝑥 ∈ 𝑋 (((𝑢𝐺𝑥) = 𝑥 ∧ (𝑥𝐺𝑢) = 𝑥) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑥) = 𝑢 ∧ (𝑥𝐺𝑦) = 𝑢))) | ||
Theorem | grpoideu 27363* | The left identity element of a group is unique. Lemma 2.2.1(a) of [Herstein] p. 55. (Contributed by NM, 14-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ (𝐺 ∈ GrpOp → ∃!𝑢 ∈ 𝑋 ∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥) | ||
Theorem | grporndm 27364 | A group's range in terms of its domain. (Contributed by NM, 6-Apr-2008.) (New usage is discouraged.) |
⊢ (𝐺 ∈ GrpOp → ran 𝐺 = dom dom 𝐺) | ||
Theorem | 0ngrp 27365 | The empty set is not a group. (Contributed by NM, 25-Apr-2007.) (New usage is discouraged.) |
⊢ ¬ ∅ ∈ GrpOp | ||
Theorem | gidval 27366* | The value of the identity element of a group. (Contributed by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ (𝐺 ∈ 𝑉 → (GId‘𝐺) = (℩𝑢 ∈ 𝑋 ∀𝑥 ∈ 𝑋 ((𝑢𝐺𝑥) = 𝑥 ∧ (𝑥𝐺𝑢) = 𝑥))) | ||
Theorem | grpoidval 27367* | Lemma for grpoidcl 27368 and others. (Contributed by NM, 5-Feb-2010.) (Proof shortened by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) ⇒ ⊢ (𝐺 ∈ GrpOp → 𝑈 = (℩𝑢 ∈ 𝑋 ∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥)) | ||
Theorem | grpoidcl 27368 | The identity element of a group belongs to the group. (Contributed by NM, 24-Oct-2006.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) ⇒ ⊢ (𝐺 ∈ GrpOp → 𝑈 ∈ 𝑋) | ||
Theorem | grpoidinv2 27369* | A group's properties using the explicit identity element. (Contributed by NM, 5-Feb-2010.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → (((𝑈𝐺𝐴) = 𝐴 ∧ (𝐴𝐺𝑈) = 𝐴) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝐴) = 𝑈 ∧ (𝐴𝐺𝑦) = 𝑈))) | ||
Theorem | grpolid 27370 | The identity element of a group is a left identity. (Contributed by NM, 24-Oct-2006.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → (𝑈𝐺𝐴) = 𝐴) | ||
Theorem | grporid 27371 | The identity element of a group is a right identity. (Contributed by NM, 24-Oct-2006.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → (𝐴𝐺𝑈) = 𝐴) | ||
Theorem | grporcan 27372 | Right cancellation law for groups. (Contributed by NM, 26-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ (𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋 ∧ 𝐶 ∈ 𝑋)) → ((𝐴𝐺𝐶) = (𝐵𝐺𝐶) ↔ 𝐴 = 𝐵)) | ||
Theorem | grpoinveu 27373* | The left inverse element of a group is unique. Lemma 2.2.1(b) of [Herstein] p. 55. (Contributed by NM, 27-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → ∃!𝑦 ∈ 𝑋 (𝑦𝐺𝐴) = 𝑈) | ||
Theorem | grpoid 27374 | Two ways of saying that an element of a group is the identity element. (Contributed by Paul Chapman, 25-Feb-2008.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → (𝐴 = 𝑈 ↔ (𝐴𝐺𝐴) = 𝐴)) | ||
Theorem | grporn 27375 | The range of a group operation. Useful for satisfying group base set hypotheses of the form 𝑋 = ran 𝐺. (Contributed by NM, 5-Nov-2006.) (New usage is discouraged.) |
⊢ 𝐺 ∈ GrpOp & ⊢ dom 𝐺 = (𝑋 × 𝑋) ⇒ ⊢ 𝑋 = ran 𝐺 | ||
Theorem | grpoinvfval 27376* | The inverse function of a group. (Contributed by NM, 26-Oct-2006.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) & ⊢ 𝑁 = (inv‘𝐺) ⇒ ⊢ (𝐺 ∈ GrpOp → 𝑁 = (𝑥 ∈ 𝑋 ↦ (℩𝑦 ∈ 𝑋 (𝑦𝐺𝑥) = 𝑈))) | ||
Theorem | grpoinvval 27377* | The inverse of a group element. (Contributed by NM, 26-Oct-2006.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) & ⊢ 𝑁 = (inv‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → (𝑁‘𝐴) = (℩𝑦 ∈ 𝑋 (𝑦𝐺𝐴) = 𝑈)) | ||
Theorem | grpoinvcl 27378 | A group element's inverse is a group element. (Contributed by NM, 27-Oct-2006.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑁 = (inv‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → (𝑁‘𝐴) ∈ 𝑋) | ||
Theorem | grpoinv 27379 | The properties of a group element's inverse. (Contributed by NM, 27-Oct-2006.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) & ⊢ 𝑁 = (inv‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → (((𝑁‘𝐴)𝐺𝐴) = 𝑈 ∧ (𝐴𝐺(𝑁‘𝐴)) = 𝑈)) | ||
Theorem | grpolinv 27380 | The left inverse of a group element. (Contributed by NM, 27-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) & ⊢ 𝑁 = (inv‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → ((𝑁‘𝐴)𝐺𝐴) = 𝑈) | ||
Theorem | grporinv 27381 | The right inverse of a group element. (Contributed by NM, 27-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) & ⊢ 𝑁 = (inv‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → (𝐴𝐺(𝑁‘𝐴)) = 𝑈) | ||
Theorem | grpoinvid1 27382 | The inverse of a group element expressed in terms of the identity element. (Contributed by NM, 27-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) & ⊢ 𝑁 = (inv‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → ((𝑁‘𝐴) = 𝐵 ↔ (𝐴𝐺𝐵) = 𝑈)) | ||
Theorem | grpoinvid2 27383 | The inverse of a group element expressed in terms of the identity element. (Contributed by NM, 27-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑈 = (GId‘𝐺) & ⊢ 𝑁 = (inv‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → ((𝑁‘𝐴) = 𝐵 ↔ (𝐵𝐺𝐴) = 𝑈)) | ||
Theorem | grpolcan 27384 | Left cancellation law for groups. (Contributed by NM, 27-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ (𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋 ∧ 𝐶 ∈ 𝑋)) → ((𝐶𝐺𝐴) = (𝐶𝐺𝐵) ↔ 𝐴 = 𝐵)) | ||
Theorem | grpo2inv 27385 | Double inverse law for groups. Lemma 2.2.1(c) of [Herstein] p. 55. (Contributed by NM, 27-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑁 = (inv‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → (𝑁‘(𝑁‘𝐴)) = 𝐴) | ||
Theorem | grpoinvf 27386 | Mapping of the inverse function of a group. (Contributed by NM, 29-Mar-2008.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑁 = (inv‘𝐺) ⇒ ⊢ (𝐺 ∈ GrpOp → 𝑁:𝑋–1-1-onto→𝑋) | ||
Theorem | grpoinvop 27387 | The inverse of the group operation reverses the arguments. Lemma 2.2.1(d) of [Herstein] p. 55. (Contributed by NM, 27-Oct-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑁 = (inv‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (𝑁‘(𝐴𝐺𝐵)) = ((𝑁‘𝐵)𝐺(𝑁‘𝐴))) | ||
Theorem | grpodivfval 27388* | Group division (or subtraction) operation. (Contributed by NM, 15-Feb-2008.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑁 = (inv‘𝐺) & ⊢ 𝐷 = ( /𝑔 ‘𝐺) ⇒ ⊢ (𝐺 ∈ GrpOp → 𝐷 = (𝑥 ∈ 𝑋, 𝑦 ∈ 𝑋 ↦ (𝑥𝐺(𝑁‘𝑦)))) | ||
Theorem | grpodivval 27389 | Group division (or subtraction) operation value. (Contributed by NM, 15-Feb-2008.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑁 = (inv‘𝐺) & ⊢ 𝐷 = ( /𝑔 ‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (𝐴𝐷𝐵) = (𝐴𝐺(𝑁‘𝐵))) | ||
Theorem | grpodivinv 27390 | Group division by an inverse. (Contributed by NM, 15-Feb-2008.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑁 = (inv‘𝐺) & ⊢ 𝐷 = ( /𝑔 ‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (𝐴𝐷(𝑁‘𝐵)) = (𝐴𝐺𝐵)) | ||
Theorem | grpoinvdiv 27391 | Inverse of a group division. (Contributed by NM, 24-Feb-2008.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝑁 = (inv‘𝐺) & ⊢ 𝐷 = ( /𝑔 ‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (𝑁‘(𝐴𝐷𝐵)) = (𝐵𝐷𝐴)) | ||
Theorem | grpodivf 27392 | Mapping for group division. (Contributed by NM, 10-Apr-2008.) (Revised by Mario Carneiro, 15-Dec-2013.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝐷 = ( /𝑔 ‘𝐺) ⇒ ⊢ (𝐺 ∈ GrpOp → 𝐷:(𝑋 × 𝑋)⟶𝑋) | ||
Theorem | grpodivcl 27393 | Closure of group division (or subtraction) operation. (Contributed by NM, 15-Feb-2008.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝐷 = ( /𝑔 ‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (𝐴𝐷𝐵) ∈ 𝑋) | ||
Theorem | grpodivdiv 27394 | Double group division. (Contributed by NM, 24-Feb-2008.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝐷 = ( /𝑔 ‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ (𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋 ∧ 𝐶 ∈ 𝑋)) → (𝐴𝐷(𝐵𝐷𝐶)) = (𝐴𝐺(𝐶𝐷𝐵))) | ||
Theorem | grpomuldivass 27395 | Associative-type law for multiplication and division. (Contributed by NM, 15-Feb-2008.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝐷 = ( /𝑔 ‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ (𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋 ∧ 𝐶 ∈ 𝑋)) → ((𝐴𝐺𝐵)𝐷𝐶) = (𝐴𝐺(𝐵𝐷𝐶))) | ||
Theorem | grpodivid 27396 | Division of a group member by itself. (Contributed by NM, 15-Feb-2008.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝐷 = ( /𝑔 ‘𝐺) & ⊢ 𝑈 = (GId‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋) → (𝐴𝐷𝐴) = 𝑈) | ||
Theorem | grponpcan 27397 | Cancellation law for group division. (npcan 10290 analog.) (Contributed by NM, 15-Feb-2008.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 & ⊢ 𝐷 = ( /𝑔 ‘𝐺) ⇒ ⊢ ((𝐺 ∈ GrpOp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → ((𝐴𝐷𝐵)𝐺𝐵) = 𝐴) | ||
Syntax | cablo 27398 | Extend class notation with the class of all Abelian group operations. |
class AbelOp | ||
Definition | df-ablo 27399* | Define the class of all Abelian group operations. (Contributed by NM, 2-Nov-2006.) (New usage is discouraged.) |
⊢ AbelOp = {𝑔 ∈ GrpOp ∣ ∀𝑥 ∈ ran 𝑔∀𝑦 ∈ ran 𝑔(𝑥𝑔𝑦) = (𝑦𝑔𝑥)} | ||
Theorem | isablo 27400* | The predicate "is an Abelian (commutative) group operation." (Contributed by NM, 2-Nov-2006.) (New usage is discouraged.) |
⊢ 𝑋 = ran 𝐺 ⇒ ⊢ (𝐺 ∈ AbelOp ↔ (𝐺 ∈ GrpOp ∧ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 (𝑥𝐺𝑦) = (𝑦𝐺𝑥))) |
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