Definition

For an agent with concepts K, budget B and horizon H, the inquiry frontier is the set of questions q for which some procedure available to the agent formulates q, making it determinate enough to pursue, within B and H (A17 §§2, 7). Formulating is neither answering nor pursuing: A17 §2’s askable set is “distinct from the investigable and the answerable questions”. Four sets differ:

  • expressible: statable in some language, in principle;
  • askable: on the frontier;
  • investigable: on the frontier, with budget left to pursue it to a stated standard;
  • answerable: having an answer that some process could find.

A question can be expressible and off the frontier. The owner’s U17: “I can’t interrogate a question that takes me more time than I have to even ask it.” A question can also be askable and unanswerable from the evidence available, as below Singer’s information bound (NOTE-1224).

The distinctions it draws

  • From legibility (TERM-064). Legibility is whether a distinction can be recovered for a task already set. The frontier is whether the task can be set at all. A17 §4: “whether the agent can construct the task that would make that distinction relevant.”
  • From the regime (TERM-065). The regime fixes a query family for a comparison. The frontier is where a query family could come from (the note on TERM-065 of 2026-10-27).
  • Movement, not only extent. Reusable specifications, such as a notation, a theory or a schema, move the frontier without enlarging the budget. They can also make other questions harder. A17 §7: “The change could be in the shape of the frontier rather than its total size.”

Why it is proposed

CLAIM-475 is stated in it, and its defeater (b) is a test of frontier movement. CLAIM-474 lists “askable without answerable” among the failures. What would settle it: adoption once the claims stated in it use one of its sets each; rejection if TERM-065 extended to generated query families serves, an extension TERM-065’s note of 2026-10-27 declined.

Note of 2026-10-29: what holds it back

CLAIM-475, the claim stated in this term, uses two of its sets: its title and defeater (a) the askable, its §7 (“questions that can meaningfully be investigated”) and defeater (b) (“formulate and pursue”) the investigable. Adoption once CLAIM-475 says which set its defeater (b) tests.