Upper and lower sequence limits
For a real sequence, lim sup xₙ=lim_N sup{k≥N}xₖ and lim inf xₙ=lim_N inf{k≥N}xₖ.
Key knowledge
For a real sequence, lim sup xₙ=lim_N sup{k≥N}xₖ and lim inf xₙ=lim_N inf{k≥N}xₖ. These tail limits exist in the extended reals and lim inf≤lim sup. A finite ordinary limit exists exactly when both are finite and equal.
Conditions and scope
- Tail suprema decrease and tail infima increase.
- Extended infinities are permitted, without defining ∞−∞.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Definitions3.33–34 and Theorem3.42, printed49–53.
2026-10-10 · Independent AI editorial review: All241 compact claims, hypotheses, displayed equations/conventions and all596 origin semantic links read; entire241-entry author exact-source inspection matrix and declared limitations reviewed. Prior105 actual inherited Mathematics/Information records read for whole-inventory breadth. Targeted independent primary sections are listed below; this does NOT claim every cited source body or every proof was independently re-read. This is AI reference-content review, not human disciplinary certification, exhaustive textbook reproduction or experimental replication. Receipt: mathematics-information-independent-content-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- math-limsup-liminf
- Revision
- university-core.1
- Structured reference record
- University core expansion