Sequences, series, summability
317 ideas in this subject. The map below lists the main ideas of the subject by area, in teaching order. 202 of its 204 ideas have a page so far.
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- ConceptSequence
A sequence is an ordered list of elements of a set, with one term for each natural number. Sequences are the basic objects of the study of limits in analysis. The node sequence gives the precise definition.
- ConceptLimit of a sequence
A sequence has a limit when its terms come and stay arbitrarily close to for large indices. Limits of sequences are the base of the notions of convergence, continuity and series in analysis. The node limit of a sequence gives the precise definition.
- PropositionUniqueness of limits
Let be a real sequence and let and be real numbers. If converges to and converges to , then .
- ConceptBounded sequence
A bounded sequence is a real sequence whose terms all lie in one fixed interval. Boundedness is a necessary condition for convergence, and it is the hypothesis of the Bolzano–Weierstrass theorem. The node bounded sequence gives the precise definition.
- ConceptMonotone sequence
A monotone sequence is a real sequence that never decreases or never increases. A bounded monotone sequence always converges. The node monotone sequence gives the precise definition.
- TheoremMonotone convergence theorem for sequences
Let be an increasing real sequence, in the sense of a monotone sequence. Assume that is bounded above. Then converges, and its limit is the supremum .
Map of the subject
Sequences and limits 30 of 30
- Sequence definition
- Limit of a sequence definition
- Uniqueness of limits statement
- Bounded sequence definition
- Monotone sequence definition
- Monotone convergence theorem for sequences statement
- Squeeze theorem statement
- Cauchy sequence definition
- Cauchy criterion for sequences statement
- Subsequence definition
- Bolzano–Weierstrass theorem statement
- Limit superior definition
- Cluster point of a sequence definition
- A sequence converges iff its liminf and limsup agree statement
- Stolz–Cesàro theorem statement
- Cesàro mean definition
- Fekete's lemma statement
- Fekete's lemma statement
- Geometric sequence example
- Arithmetic progression example
- e as the limit of (1 + 1/n)^n statement
- Euler–Mascheroni constant object
- Rate of convergence definition
- Big O notation definition
- Asymptotic equivalence definition
- Equidistribution modulo one definition
- Weyl's criterion statement
- Kronecker's approximation theorem statement
- Recurrence relation definition
- Fixed-point iteration definition
Series: basic notions 32 of 34
- Series definition
- Partial sum definition
- Convergent series definition
- Divergent series definition
- Sum of a series definition
- Term test statement
- Cauchy criterion for series statement
- Geometric series example
- Harmonic series example
- Harmonic number definition
- Harmonic numbers grow like log n statement
- p-series test example
- Basel problem statement
- Telescoping series example
- Alternating series definition
- Alternating harmonic series example
- Leibniz formula for pi statement
- Grandi's series example
- 1 + 2 + 3 + 4 + ⋯ example
- 1 + 2 + 3 + 4 + ⋯ example
- 1 + 1 + 1 + 1 + ⋯ example
- 1 − 1 + 2 − 6 + 24 − 120 + ⋯ example
- Divergence of the sum of the reciprocals of the primes statement
- Kempner series example
- Riemann zeta function as a series example
- Dirichlet series definition
- power series definition
- radius of convergence definition
- Cauchy–Hadamard theorem statement
- Taylor series definition
- The exponential series has infinite radius of convergence example
- Fourier series definition
- Lambert series definition
- Hypergeometric series definition
Convergence tests 20 of 20
- Convergence tests concept
- Comparison test statement
- Limit comparison test statement
- Ratio test statement
- Root test statement
- Integral test statement
- Cauchy condensation test statement
- Schlömilch's generalization of the condensation test statement
- Alternating series test statement
- Dirichlet's test statement
- Abel's test statement
- Raabe's test statement
- Gauss's test statement
- Kummer's test statement
- Bertrand's test statement
- Summation by parts statement
- Abel's summation formula statement
- Euler–Maclaurin formula statement
- Kronecker's lemma statement
- Abel–Dini theorem statement
Absolute and conditional convergence, rearrangements, products of series 13 of 13
- Absolute convergence definition
- Conditional convergence definition
- Unconditional convergence definition
- Riemann rearrangement theorem statement
- Lévy–Steinitz theorem statement
- Dvoretzky–Rogers theorem statement
- Cauchy product definition
- Mertens' theorem on Cauchy products statement
- Summation of families over arbitrary index sets definition
- Weierstrass M-test statement
- Uniform convergence of series definition
- Tannery's theorem statement
- Dini's theorem statement
Infinite products 9 of 9
- Infinite product definition
- Convergence of an infinite product definition
- An infinite product converges iff its series of logarithms converges statement
- Wallis product statement
- Euler product for multiplicative functions statement
- Euler's sine product statement
- Weierstrass factorization theorem statement
- Viète's formula statement
- q-Pochhammer symbol definition
Multiple series and sequences 7 of 7
- Double series definition
- Fubini's theorem for series statement
- Interchange of summation order statement
- Double sequence definition
- Pringsheim convergence definition
- Moore–Osgood theorem statement
- Eisenstein series as a double series example
Continued fractions and limit processes 11 of 11
- Continued fraction definition
- Continued fraction definition
- Convergents of a continued fraction definition
- Fundamental recurrence formulas statement
- Śleszyński–Pringsheim theorem statement
- Van Vleck's theorem statement
- Euler's continued fraction formula statement
- Padé approximant definition
- Infinite compositions of functions definition
- Nested radical example
- Iterated exponentiation example
Series acceleration 8 of 8
- Series acceleration concept
- Aitken's delta-squared process definition
- Richardson extrapolation definition
- Shanks transformation definition
- Euler transform definition
- Van Wijngaarden transformation definition
- Wynn's epsilon algorithm definition
- Levin-type transformations definition
General summability methods 9 of 9
- Summability method concept
- Regular summability method definition
- Linear and stable summation methods definition
- Matrix summability method definition
- Silverman–Toeplitz theorem statement
- Kojima–Schur theorem statement
- Steinhaus theorem on regular methods statement
- Consistency of summability methods concept
- Mazur–Orlicz theorem statement
Special summability methods 20 of 20
- Cesàro summation definition
- Hölder summation definition
- Abel summation definition
- Abel's theorem statement
- Borel summation definition
- Euler summation definition
- Nörlund mean definition
- Riesz mean definition
- Hausdorff summation definition
- Lindelöf summation definition
- Mittag-Leffler summation definition
- Lambert summation definition
- Ramanujan summation definition
- Zeta function regularization definition
- Euler–Boole summation definition
- Fejér's theorem statement
- Fejér kernel definition
- Abel–Poisson summation of Fourier series definition
- Frobenius theorem on Cesàro and Abel summability statement
- Mittag-Leffler star definition
Abelian and Tauberian theorems 15 of 15
- Abelian and Tauberian theorems concept
- Tauber's theorem statement
- Hardy's Tauberian theorem for Cesàro means statement
- Littlewood's Tauberian theorem statement
- Hardy–Littlewood Tauberian theorem statement
- Karamata's Tauberian theorem statement
- Wiener's Tauberian theorem statement
- Wiener–Ikehara theorem statement
- Tauberian condition definition
- Slowly varying function definition
- Regular variation definition
- High indices theorem statement
- Hadamard gap theorem statement
- Hadamard gap theorem statement
- Fabry gap theorem statement
Absolute and strong summability 4 of 4
- Absolute summability definition
- Strong Cesàro summability definition
- Almost convergence definition
- Lorentz's characterization of almost convergence statement
Functional analytic methods and sequence spaces 11 of 11
- Sequence space definition
- Space of convergent sequences example
- Space of null sequences example
- Lp space definition
- Bounded sequences ℓ∞ example
- Banach limit definition
- Köthe–Toeplitz dual definition
- FK-space definition
- BK-space definition
- Summability field of a matrix method definition
- Schauder basis definition
Abstract settings for convergence 8 of 8
- Filter limit definition
- Net definition
- Statistical convergence definition
- Natural density definition
- Convergence along an ultrafilter definition
- Summation in topological groups concept
- Series in Banach spaces concept
- Orlicz–Pettis theorem statement
Asymptotic expansions and divergent series in analysis 5 of 5
- Asymptotic expansion definition
- Stirling's series example
- Borel–Ritt theorem statement
- Resurgent function definition
- Watson's lemma statement
More ideas in this subject
Concepts 19
- Optimal truncation
- Real sequence
- Contractive sequence
- Sequence tending to infinity
- Algebra of limits
- Convergent sequence
- Limit inferior
- Pointwise convergence
- Rearrangement of a series
- Cesàro means of Fourier series
- Divergent sequence
- Uniform convergence
- Sequence of functions
- Uniform convergence on a set
- Series of functions
- Improper integral
- Absolutely convergent improper integral
- Uniformly Cauchy sequence of functions
- Normal convergence
Theorems and results 33
- Abel–Plana formula
- Epsilon-N definition of the limit of a sequence
- Sum of a finite geometric series
- Cauchy sequences are bounded
- Cesàro means of a convergent sequence converge
- Every sequence has a monotone subsequence
- Final value theorem
- Initial value theorem
- Limit of a sum of sequences
- Limits preserve non-strict inequalities
- Convergent sequences are Cauchy
- Subsequences of a convergent sequence converge to the same limit
- Convergent sequences are bounded
- Decreasing sequence bounded below converges
- Limit of a product of sequences
- Limit of a quotient of sequences
- Cauchy product of absolutely convergent series
- Rearrangements of an absolutely convergent series have the same sum
- Uniform limit theorem
- A series of nonnegative terms converges iff its partial sums are bounded
- Harmonic series diverges
- Abelian theorems for integral transforms
- Uniform limits commute with integration
- Absolutely convergent series converge
- Comparison test for improper integrals
- Term-by-term integration
- Divergence part of the ratio test
- Power series converge uniformly on smaller discs inside the radius of convergence
- Continuity of the sum of a uniformly convergent series of functions
- Uniform convergence of derivatives allows term-by-term differentiation
- Term-by-term differentiation
- Absolutely convergent series in a Banach space converge
- Tauberian theorems for integral transforms
Examples 12
- Divergent asymptotic series
- The nth root of n tends to 1
- The sequence 1/n tends to zero
- The sequence r^n tends to infinity for r > 1
- The sequence r^n tends to zero for |r| < 1
- Decimal expansion as a series
- Sum of the reciprocals of the factorials
- Dirichlet integral
- Gaussian integral
- Integral of exp(-x) over the half line
- Improper integral of x^p on an unbounded interval
- Basel problem via Fourier series
Counterexamples 1
Definitions 94
- Sequence
- Optimal truncation
- Pringsheim convergence
- Real sequence
- Slowly varying function
- Subsequence
- Bounded sequence
- Cauchy sequence
- Cesàro mean
- Contractive sequence
- Double sequence
- Geometric sequence
- Infinite product
- Limit of a sequence
- Monotone sequence
- Regular variation
- Sequence tending to infinity
- Series
- Almost convergence
- Alternating series
- Cauchy product
- Cluster point of a sequence
- Convergent sequence
- Hausdorff summation
- Limit inferior
- Limit superior
- Partial sum
- Pointwise convergence
- Rate of convergence
- Rearrangement of a series
- Zeta function regularization
- Cesàro means of Fourier series
- Divergent sequence
- Fejér kernel
- Richardson extrapolation
- Statistical convergence
- Summability method
- Uniform convergence
- Consistency of summability methods
- Double series
- Euler summation
- Euler transform
- Linear and stable summation methods
- Matrix summability method
- Riesz mean
- Series acceleration
- Strong Cesàro summability
- Summability field of a matrix method
- Summation in topological groups
- Uniform convergence on a set
- Van Wijngaarden transformation
- Aitken's delta-squared process
- Cesàro summation
- Convergence of an infinite product
- Convergent series
- Filter limit
- Hölder summation
- Nörlund mean
- Series of functions
- Absolute convergence
- Absolute summability
- Divergent series
- Levin-type transformations
- Lindelöf summation
- Regular summability method
- Sum of a series
- Abel summation
- Abel–Poisson summation of Fourier series
- Conditional convergence
- Convergence tests
- Uniform convergence of series
- Abelian and Tauberian theorems
- Borel summation
- Improper integral
- Absolutely convergent improper integral
- Convergence along an ultrafilter
- Euler–Boole summation
- Unconditional convergence
- Ramanujan summation
- Lambert summation
- Resurgent function
- Shanks transformation
- Tauberian condition
- Wynn's epsilon algorithm
- Uniformly Cauchy sequence of functions
- Infinite compositions of functions
- Mittag-Leffler summation
- Summation of families over arbitrary index sets
- Normal convergence
- Fixed-point iteration
- Sequence space
- FK-space
- Banach limit
- Series in Banach spaces