{
  "slug": "reuse-time",
  "term": "Reuse time",
  "aliases": [
    "Reuse interval",
    "Inter-reference interval"
  ],
  "definition": "Reuse time is the elapsed logical or physical time between consecutive accesses to the same data identity.",
  "note": "State the clock and endpoint convention: in a request-index clock, subtracting the previous index from the current index gives one for immediate repetition. This is not the count of distinct intervening identities. A cold-start first appearance has no observed preceding access. [locality-theory]\n\nAn unordered reuse-time histogram does not uniquely determine the reuse-distance histogram. This is an established non-equivalence, not a failure of every statistical estimator. [locality-theory]\n\nExact example: AACBAB and ABAABC each access A three times, B twice and C once, with one interval each of lengths 1, 2 and 3. Empty two-slot LRU misses 4/6 and 3/6 respectively. The ordered interval sequences differ. These are constructed equal-size traces with immediate demand admission, not measured SSD performance. [example]",
  "status": "research",
  "advantages": [],
  "limitations": [],
  "related": [
    "reuse-distance",
    "working-set",
    "miss-ratio-curve",
    "lru-replacement"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-11-12",
  "citations": [
    {
      "id": "locality-theory",
      "title": "Yuan, Ding, Smith, Denning and Zhang. A Relational Theory of Locality. ACM TACO 16(3), article 33 (2019), sections 2.2-2.3.2. DOI: 10.1145/3341109.",
      "url": "https://denninginstitute.com/pjd/PUBS/TACO-2019.pdf",
      "accessed": "2026-11-12"
    },
    {
      "id": "example",
      "title": "Hesela. Exact reuse-time histogram counterexample, assumptions and reproducible JSON.",
      "url": "https://hesela.dev/research/reuse-time.json",
      "accessed": "2026-11-12"
    }
  ],
  "provenance": [
    "Primary-paper review and exact constructed arithmetic. No new theorem, hardware experiment or performance replication."
  ]
}