Northbridge solutions

25 pages in this book.

Page	What it is for
nb-01 solutions — First permit: facts, a rule and a question	Setup: vehicle_registered(ann) asserted, resident(ann) not asserted. Question: status of truth(permit_eligible(ann)) under the probe program.
nb-02 exercise — solution	NEITHER. The badge supports eligibility through BadgeEligibility, but the defeater FraudBlocksBadge removes that support without deriving the negation (defeat permit_eligible(a) is not then not permit_eligible(a) — compare FraudBlocksBadge (lines 47–51) with FinesRefusal (lines 30–34) in packs/examples/language-demo/permits/package.law). With support removed and no denial derived, neither side has support.
nb-03 solutions: Exceptions and conflicting rules	Bob holds a disability badge and has outstanding fines recorded.
nb-04 solutions — The permit fee	Answer: 0.2, the second row (when months >= 12 => 0.2).
nb-05 solutions — Who counts as a suitable applicant	Answer: TRUE_ONLY. The two elements are the definition central_resident(ann) (resident and living in the centre) and the rule conclusion large_household(ann) (count of her household members reaches LARGE_HOUSEHOLD, i.e. 4).
nb-06 solutions — When the register may stay silent	Answer: FALSE_ONLY.
nb-07 solutions — A document is not yet a proven fact	Answer: authentic(d, "urn:demo:northbridge:verifier", "verified").
nb-08 solutions — Which edition applies and when the term expires	Answer: NEITHER — no rule fires.
nb-09 solutions — From permit to duties and powers	Answer: replace the explicit denial with the positive fact for SATISFIED; drop the denial (assert neither) for UNDETERMINED.
nb-10 solutions — A procedure with parallel checks	Answer: the case stays Draft — current_state(st1, Draft) is TRUE_ONLY and any Filed or Review query is NEITHER.
nb-11 solutions — Appeal: reading, judgment and precedent	Answer: second_vehicle(ann) plus permit_eligible(ann) (via resident + vehicle_registered); the clerk’s file fails the eligibility premise.
nb-12 solutions — Allocation in rounds	Answer: the resident filing; the rounds are empty without seed test already proves the outcome.
nb-13 solutions — Repeatable norms without copying	Answer: with files_late only, late_fined is NEITHER and late_noticed is TRUE_ONLY; adding repeat_late flips only late_fined to TRUE_ONLY. The change belongs to WithRecord/applicable.
nb-14 solutions — Why this answer and what would change it	Answer: big_bill(1) is NEITHER; big_bill(12) is TRUE_ONLY; explain lists the BigBill rule application and the b12 assertion.
nb-15 solutions — Quantities and dimensions	Answer: 5 km gives TRUE_ONLY (melded scalar 5000/1); 22 kW gives NEITHER — no scalar is melded at all.
nb-16 solutions — Exact computation and proven bounds	Answer: TRUE_ONLY. The fraction form is the exact value, not a terminating-decimal approximation.
nb-17 solutions — Numeric families and support boundaries	Answer: sqrt_self() is TRUE_ONLY; sqrt_x() is NEITHER. The left-hand sides are identical calls; the right-hand sides differ — self versus a foreign derivation.
nb-18 solutions — Vocabulary and package composition	Answer: NEITHER. The resident half holds; the counter half has no support, so the conjunction never fires.
nb-19 solutions — Unknown, presumed and deemed	Setup: demo.northbridge.unknown (packs/examples/language-demo/unknown/), suite 17/17 green. Command for every check below:
nb-20 solutions — Sources, time, and outside data	Three places change, in this order — bytes, hashes, delta:
nb-21 solutions — Positions live, files move, readings decide	Answer: the sublet fact (sublet-ann); the power without grounds does not operate test already proves the outcome.
nb-22 solutions	cause = some repeat_inquirer in RepeatFee: the generated rule carries if some cause as g { when g(subject); }, so without a repeat_inquirer fact the premise is unsatisfied and the rule cannot fire — callback_fee is NEITHER, exactly what fee needs the repeat record asserts. cause = none in FirstNotice: the optional premise vanishes, so inquiry_filed alone suffices and callback_notice is TRUE_ONLY. If you predicted NEITHER for the fee, you read the option correctly; if you predicted FALSE_ONLY, re-read nb-01 — an unsatisfied premise is silence, not a refusal.
nb-23 solutions — Numbers and the standard library	Answer: the four-way split fires at 470 KZT; the three-way split carries INEXACT_DIVISION instead of a rounded amount.
nb-24 solutions — Neighbor constructs, nine mistakes and three decision tasks	Bob is badge-holding and fined, lives in the outer zone, and pays the fee three times at 10 EUR.
nb-25 solutions — Capstone case	Bob files: resident with a registered car, twelve-month term, filed 1 March, no hold, single filing copy.