Dedekind cut
E634836
A Dedekind cut is a method of constructing the real numbers from the rational numbers by partitioning them into two nonempty sets that capture the idea of a "cut" point on the number line.
All labels observed (1)
| Label | Occurrences |
|---|---|
| Dedekind cut canonical | 2 |
How this entity was disambiguated
This entity first appeared as the object of triple T7011037 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
Target entity: Dedekind cut Context triple: [Richard Dedekind, knownFor, Dedekind cut]
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A.
Cantor set
The Cantor set is a classic fractal subset of the real line formed by repeatedly removing the open middle third of intervals, notable for being uncountable, perfect, nowhere dense, and having zero Lebesgue measure.
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B.
Surreal numbers
Surreal numbers are a class of numbers introduced by John H. Conway that form an extensive ordered field encompassing the real numbers, infinite quantities, and infinitesimals within a unified framework.
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C.
Hausdorff
Hausdorff is a topological separation property requiring that any two distinct points in a space can be enclosed in disjoint open sets.
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D.
Banach–Tarski paradox
The Banach–Tarski paradox is a theorem in set-theoretic geometry stating that a solid ball in 3‑dimensional space can be decomposed into finitely many non-measurable pieces and reassembled into two identical copies of the original ball, highlighting counterintuitive consequences of the axiom of choice.
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E.
Archimedean property of real numbers
The Archimedean property of real numbers is a fundamental axiom stating that for any real number, there exists a natural number larger than it, ensuring there are no infinitely large or infinitesimally small elements in the real number system.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
Target entity: Dedekind cut Target entity description: A Dedekind cut is a method of constructing the real numbers from the rational numbers by partitioning them into two nonempty sets that capture the idea of a "cut" point on the number line.
-
A.
Cantor set
The Cantor set is a classic fractal subset of the real line formed by repeatedly removing the open middle third of intervals, notable for being uncountable, perfect, nowhere dense, and having zero Lebesgue measure.
-
B.
Surreal numbers
Surreal numbers are a class of numbers introduced by John H. Conway that form an extensive ordered field encompassing the real numbers, infinite quantities, and infinitesimals within a unified framework.
-
C.
Hausdorff
Hausdorff is a topological separation property requiring that any two distinct points in a space can be enclosed in disjoint open sets.
-
D.
Banach–Tarski paradox
The Banach–Tarski paradox is a theorem in set-theoretic geometry stating that a solid ball in 3‑dimensional space can be decomposed into finitely many non-measurable pieces and reassembled into two identical copies of the original ball, highlighting counterintuitive consequences of the axiom of choice.
-
E.
Archimedean property of real numbers
The Archimedean property of real numbers is a fundamental axiom stating that for any real number, there exists a natural number larger than it, ensuring there are no infinitely large or infinitesimally small elements in the real number system.
- F. None of above. chosen
Statements (47)
| Predicate | Object |
|---|---|
| instanceOf |
construction of real numbers
ⓘ
mathematical concept ⓘ order-theoretic structure ⓘ |
| alternativeView | pair (A,B) of subsets of Q with A union B = Q and A less than B ⓘ |
| appearsIn |
axiomatic construction of the real numbers
ⓘ
foundations of analysis ⓘ foundations of mathematics ⓘ |
| basedOn | rational numbers ⓘ |
| captures | idea of a cut point on the number line ⓘ |
| constructionType | completion of an ordered field ⓘ |
| contrastsWith |
decimal expansion representation of real numbers
ⓘ
geometric construction of real numbers as points on a line ⓘ |
| correspondsTo |
a point on the real number line
ⓘ
a unique real number ⓘ |
| definition |
a partition of the rational numbers into two nonempty sets A and B such that every element of A is less than every element of B
ⓘ
a subset A of the rationals that is nonempty, not all of Q, downward closed, and has no greatest element ⓘ |
| distinguishes | rational and irrational real numbers ⓘ |
| ensures |
least upper bound property of the real numbers
ⓘ
order completeness of the real numbers ⓘ |
| equivalentTo | Cauchy sequence construction up to isomorphism of ordered fields ⓘ |
| field |
number theory
ⓘ
order theory ⓘ real analysis ⓘ set theory ⓘ |
| formalizedAs | lower set of Q with no maximum ⓘ |
| generalizationOf | Dedekind completion of a linearly ordered set ⓘ |
| hasOperation |
addition of cuts
ⓘ
multiplication of cuts ⓘ order relation induced by set inclusion ⓘ |
| introducedBy | Richard Dedekind NERFINISHED ⓘ |
| introducedIn | 19th century ⓘ |
| namedAfter | Richard Dedekind NERFINISHED ⓘ |
| property |
downward closed in the usual order on the rationals
ⓘ
has no greatest rational element ⓘ nonempty lower set of the rationals ⓘ proper subset of the rationals ⓘ |
| relatedTo | Cauchy sequence construction of the reals ⓘ |
| represents |
irrational real numbers by cuts whose complement has no least element
ⓘ
rational real numbers by cuts with a greatest element in the upper complement ⓘ |
| requires |
Archimedean property of the rationals
ⓘ
total order on the rational numbers ⓘ |
| usedFor | constructing the real numbers from the rational numbers ⓘ |
| usedIn |
constructive analysis
ⓘ
order-completion of ordered sets ⓘ |
| usedToDefine | complete ordered field of real numbers ⓘ |
| yieldsStructure |
complete densely ordered set without endpoints
ⓘ
complete ordered field isomorphic to the real numbers ⓘ |
How these facts were elicited
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Subject: Dedekind cut Description of subject: A Dedekind cut is a method of constructing the real numbers from the rational numbers by partitioning them into two nonempty sets that capture the idea of a "cut" point on the number line.
Referenced by (2)
Full triples — surface form annotated when it differs from this entity's canonical label.