{
  "title": "Unexpected hanging paradox: two-day and three-day check",
  "description": "Which class days can hold a surprise test, as announced, in a two-day week and in a Monday, Wednesday and Friday week, under four readings of what the student knows on the evening before each day: the announcement on every evening; only that a test is coming; the announcement until knowing it would pin the day; nothing. For each reading, the evening-by-evening possibilities the student cannot rule out, the days on which a surprise is possible, and the chance that a day drawn at random is no surprise. Validity only: no reading is judged correct. Computed 2026-10-31 in exact fractions, two ways. License CC BY 4.0.",
  "license": "CC BY 4.0",
  "license_url": "https://creativecommons.org/licenses/by/4.0/",
  "creator": "Puzzles, Charts & Dilemmas",
  "page": "https://puzzleschartsanddilemmas.com/puzzles/unexpected-hanging-paradox/",
  "derived_from": [
    "Computed by Puzzles, Charts & Dilemmas from the argument in standard form on this page",
    "Roy Sorensen, Epistemic Paradoxes, Stanford Encyclopedia of Philosophy (substantive revision 2022-03-03), https://plato.stanford.edu/entries/epistemic-paradoxes/ (facts paraphrased, no text reproduced), sections 1, 1.2, 2 and 5.4"
  ],
  "method": "Compiled by Puzzles, Charts & Dilemmas from the data listed"
}