{
  "id": "programming.functions.base-case-not-needed",
  "uri": "https://open-misconceptions.github.io/miscon-data/m/programming.functions.base-case-not-needed",
  "uuid": "09dac977-0121-45e8-8a5c-0aa059faf59c",
  "version": "0.1.2",
  "status": "draft",
  "trust": "low",
  "title": "A recursive function stops by itself",
  "statement": "A recursive function stops calling itself when there is nothing left to do, so it does not need an explicit base case.",
  "kind": "misapplied-analogy",
  "domain": "programming.functions",
  "about": [
    {
      "scheme": "Miscon",
      "uri": "https://open-misconceptions.github.io/miscon-data/c/programming.functions.base-case"
    }
  ],
  "level_band": [
    "middle",
    "secondary",
    "undergraduate"
  ],
  "locale": "en",
  "evidence_patterns": [
    {
      "item_shape": "predict the behaviour of a recursive function with no base case",
      "signature": "predicts termination with a sensible answer",
      "example": {
        "item": "def count_down(n):\n    print(n)\n    count_down(n - 1)\ncount_down(3)",
        "expected": "3 2 1 0 -1 ... until the recursion limit is hit",
        "response": "3 2 1"
      }
    },
    {
      "item_shape": "write a recursive function",
      "signature": "omits the base case",
      "example": {
        "item": "Write factorial(n) recursively.",
        "expected": "if n == 0: return 1\nreturn n * factorial(n - 1)",
        "response": "return n * factorial(n - 1)"
      }
    }
  ],
  "discriminators": {
    "vs_slip": "A slip is one forgotten base case the learner adds when asked how it stops. The belief is the answer 'it stops when n runs out'.",
    "vs": {
      "programming.functions.recursion-as-loop": "Loop-model holders often include a base case but expect only one copy of the variables; base-case omitters expect the function to stop on its own."
    }
  },
  "relations": {
    "conflicts_with": [
      {
        "external": "https://open-misconceptions.github.io/miscon-data/c/programming.functions.base-case",
        "label": "A recursive function stops only when a base case returns"
      }
    ],
    "resolved_by": [
      {
        "external": "https://open-misconceptions.github.io/miscon-data/c/programming.functions.base-case",
        "label": "A recursive function stops only when a base case returns"
      },
      {
        "external": "https://open-misconceptions.github.io/miscon-data/c/programming.functions.recursion",
        "label": "Each recursive call has its own activation with its own variables"
      }
    ],
    "confusable_with": [
      "programming.functions.recursion-as-loop"
    ]
  },
  "alignments": [
    {
      "scheme": "progmiscon",
      "code": "Scratch/BaseCaseNotNeeded",
      "uri": "https://progmiscon.org/misconceptions/Scratch/BaseCaseNotNeeded",
      "relation": "close-match"
    }
  ],
  "provenance": {
    "sources": [
      {
        "type": "inventory",
        "citation": "Chiodini, L., Moreno Santos, I., Gallidabino, A., Tafliovich, A., Santos, A. L., & Hauswirth, M. (2021). A curated inventory of programming language misconceptions. In Proceedings of the 26th ACM Conference on Innovation and Technology in Computer Science Education (ITiCSE '21), 380-386.",
        "doi": "10.1145/3430665.3456343",
        "url": "https://progmiscon.org/",
        "note": "Inventory consulted for the misconception name and scope only; progmiscon publishes no licence for its text, so Open Misconceptions' statements and examples are written independently."
      },
      {
        "type": "paper",
        "citation": "Kahney, H. (1983). What do novice programmers know about recursion? In Proceedings of the SIGCHI Conference on Human Factors in Computing Systems (CHI '83), 235-239.",
        "doi": "10.1145/800045.801618"
      },
      {
        "type": "paper",
        "citation": "Götschi, T., Sanders, I., & Galpin, V. (2003). Mental models of recursion. In Proceedings of the 34th SIGCSE Technical Symposium on Computer Science Education (SIGCSE '03), 346-350.",
        "doi": "10.1145/611892.612004"
      }
    ],
    "origin": "llm-drafted",
    "notes": "Drafted from the cited literature for the Open Misconceptions seed pack; statement, examples and discriminators are original text. Awaiting maintainer review."
  },
  "history": {
    "changelog": [
      {
        "version": "0.1.1",
        "date": "2026-09-05",
        "change": "Schema 0.2 migration: about/alignments carry a free-string scheme (corestandards.org URLs relabelled CCSS where present); trust computed from reviews[] (none yet, so low); no change to the statement or evidence."
      },
      {
        "version": "0.1.2",
        "date": "2026-09-07",
        "change": "Re-kinded from the withdrawn `missing-prerequisite` to `misapplied-analogy`: the belief carries everyday stopping-when-done reasoning, and loop intuition, into recursion, which is a belief the learner holds rather than an absence."
      }
    ]
  },
  "license": "CC-BY-4.0"
}