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Presumptions and fictions: corpus forms

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# Presumptions and fictions: corpus forms

Breakdown of real fragments: package identifier, human act name, form rating
(exemplary / debatable / wrong form choice) and why.

## Law

### 1. EU air passenger rights — presumption with a contrary exception (exemplary)

Package `eu.transport.air_passenger_rights` (EU air passenger rights, Regulation 261/2004),
cancellation:

```law
presumption PassengerUninformedUnlessCarrierProves(p: Passenger, f: Flight) {
    ...
    when confirmed_reservation(p, f) and cancellation(f);
    presume passenger_treated_as_uninformed(p, f);
    unless carrier_proved_notification(p, f)
        then not passenger_treated_as_uninformed(p, f);
}
```

Exemplary: the burden of proving notification is on the carrier (ground +
presumption + exception with priority). The contrary `then not …`
clause gives the rebuttal victory with a Refuted inference — unlike
the bare clause of the section’s teaching example, which gives Not established, not refuted.
The “bare vs contrary” pair in one research is deliberate.

### 2. German Civil Code — possessory ownership presumption (exemplary)

Package `de.bgb.besitz_eigentum` (German Civil Code, possession and ownership):

```law
presumption VermutungDesEigentumsFuerDenBesitzer(s: Sache, p: Person) {
```

Possession as the ground of the ownership assumption. Exemplary as a
proof scheme; exception details are in the package body.

### 3. German Civil Code — recorded-right presumption (exemplary)

Package `de.bgb.besitz_eigentum` (German Civil Code, registered rights)
— `presumption VermutungDesEingetragenenRechts(r: Recht, p: Person)`.
A land-register entry as the ground. Same form, different ground — the
presumption scheme stable across grounds.

### 4. Saudi tort — causation presumption (exemplary)

Package `sa.civil_transactions.tort_enrichment` (Saudi civil transactions, tort) —
`presumption DirectActorCausedDamage(a: HarmfulAct)`;
vicarious liability — `presumption OwnerIsKeeper(p: Person,
t: Thing)`. Presumptions as burden allocation in tort — a subject-matter
pair to the procedural EU261 form.

## Legal history and custom

### 5. Calendar Act 1750 — pure fiction (exemplary)

Package `gb.corpus.calendar_act_1750` (Calendar Act 1750, Great Britain), preserved natural day:

```law
fiction FairOrMartPreservesNaturalDay strict {
    ...
    for e: FixedEvent;
    when held_with_fair_or_mart(e);
    deem natural_day_category(e);
}
```

A fair “holds to the natural day” — equation without “if”:
`strict` strength mandatory and present. Exemplary.

### 6. Queue customary law — announced-absence presumption (exemplary)

Package `usus.corpus.ochered` (queue customary law) —
`presumption AnnouncedAbsenceHoldsThePlace(q: Queue, p: Person)`.
Announced absence holds the queue place until… — a grounded default in
customary law.

## Science

### 7. Doctrine chemistry — presumption and fiction side by side (debatable)

Package `chem.rules` (doctrine chemistry rules) —
`presumption ChloridePresumedSoluble(s: Salt, c: Cation)`;
oxidation — `fiction BondsDeemedIonic strict`.
Debatable, not exemplary: the “counts as soluble” link nowhere records
whether the exception list is closed (see the negation section’s note on
debatable solubility): it is unclear whether Not established, not refuted means “soluble” or “not checked”. The ionic-bond
fiction is exemplary as a device (modelling equation).