Cauchy sequence

E239283

A Cauchy sequence is a sequence whose terms become arbitrarily close to each other as the sequence progresses, providing a fundamental criterion for convergence in metric and normed spaces.

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All labels observed (2)

Statements (46)

Predicate Object
instanceOf mathematical concept
sequence
characterizes convergence in complete metric spaces
codomain metric space
contrastsWith pointwise definition of limit
definedIn metric space
normed vector space
topological vector space
domain elements of a metric space
exampleOf sequence defined by internal closeness rather than external limit point
field functional analysis
mathematical analysis
topology
generalizationOf Cauchy sequence of complex numbers
Cauchy sequence of real numbers
hasCategory foundational concept in metric space theory
foundational concept in real analysis
hasDefinition Cauchy sequence self-linksurface differs
surface form: A sequence (x_n) in a metric space (X,d) is Cauchy if for every ε > 0 there exists N such that for all m,n ≥ N, d(x_m,x_n) < ε.
hasEquivalentFormulation for every ε > 0 there exists N such that for all k ≥ 0, d(x_{N+k},x_N) < ε
for every ε > 0 there exists N such that for all n ≥ N, d(x_n,x_N) < ε
hasHistoricalRole formalization of convergence in analysis
hasLogicalForm ∀ε>0 ∃N ∀m,n≥N : d(x_m,x_n)<ε
hasProperty every convergent sequence in a metric space is Cauchy
in a complete metric space every Cauchy sequence converges
in an incomplete metric space a Cauchy sequence may fail to converge
in ℚ with the usual metric some Cauchy sequences do not converge in ℚ
in ℝ with the usual metric every Cauchy sequence converges
hasType sequence indexed by natural numbers
implies bounded sequence in a metric space
namedAfter Augustin-Louis Cauchy
relatedTo Cauchy completion
Cauchy criterion for series
Cauchy filter
Cauchy net
complete metric space
convergent sequence
requiresStructure distance function
metric
usedAs criterion for convergence
usedIn Banach space theory
Hilbert space theory
analysis of series and infinite products
construction of real numbers from rationals
definition of completeness of a metric space
proofs of convergence theorems
usedToDefine completion of a metric space via equivalence classes of Cauchy sequences

Referenced by (3)

Full triples — surface form annotated when it differs from this entity's canonical label.

Augustin-Louis Cauchy knownFor Cauchy sequence
Augustin-Louis notableFor Cauchy sequence
subject surface form: Augustin-Louis Cauchy
Cauchy sequence hasDefinition Cauchy sequence self-linksurface differs
this entity surface form: A sequence (x_n) in a metric space (X,d) is Cauchy if for every ε > 0 there exists N such that for all m,n ≥ N, d(x_m,x_n) < ε.