Exception from an exception

Intention

I want to restore the general conclusion when there is an exception from a prohibition.

Incorrect form and why it stays silent

unless restored(p) then allowed(p);
unless special(p) then not allowed(p);

A later proviso takes priority over an earlier one. Reordering does not preserve the chain of carve-outs.

Correct form

language "law.core" version "0.2";
package recipes.b.r02 version "0.1.0";
namespace "urn:recipe:b-rules:02";

entity Person;
relation eligible(p: Person);
relation special(p: Person);
relation allowed(p: Person);
relation restored(p: Person);
rule General defeasible {
    for p: Person; when eligible(p); then allowed(p);
    unless special(p) then not allowed(p);
    unless restored(p) then allowed(p);
}
relation reversed(p: Person);
rule Reversed defeasible {
    for p: Person; when eligible(p); then reversed(p);
    unless restored(p) then reversed(p);
    unless special(p) then not reversed(p);
}

Frozen execution scene

Facts and choice	Question	Answer
general case	`truth(allowed(entity_ref("urn:recipe:b-rules:02:p")))`	`TRUE_ONLY` / `COMPUTED`
exception	`truth(allowed(entity_ref("urn:recipe:b-rules:02:p")))`	`FALSE_ONLY` / `COMPUTED`
carve-out from the exception	`truth(allowed(entity_ref("urn:recipe:b-rules:02:p")))`	`TRUE_ONLY` / `COMPUTED`
last proviso removed	`truth(allowed(entity_ref("urn:recipe:b-rules:02:p")))`	`FALSE_ONLY` / `COMPUTED`
same facts, reverse order	`truth(reversed(entity_ref("urn:recipe:b-rules:02:p")))`	`FALSE_ONLY` / `COMPUTED`

general case

test "general case" {
    given {
        context {
            legal_time @2026-09-13;
            decision_time @2026-09-13T09:00:00+05:00;
            knowledge_time @2026-09-13T09:00:00+05:00;
            timezone "Asia/Almaty";
        }
        assert eligible(entity_ref("urn:recipe:b-rules:02:p"));
    }
    evaluate truth(allowed(entity_ref("urn:recipe:b-rules:02:p")));
    expect truth_status == TRUE_ONLY;
    expect evaluation_status == COMPUTED;
}

exception

test "exception" {
    given {
        context {
            legal_time @2026-09-13;
            decision_time @2026-09-13T09:00:00+05:00;
            knowledge_time @2026-09-13T09:00:00+05:00;
            timezone "Asia/Almaty";
        }
        assert eligible(entity_ref("urn:recipe:b-rules:02:p")); assert special(entity_ref("urn:recipe:b-rules:02:p"));
    }
    evaluate truth(allowed(entity_ref("urn:recipe:b-rules:02:p")));
    expect truth_status == FALSE_ONLY;
    expect evaluation_status == COMPUTED;
}

exception to exception

test "exception to exception" {
    given {
        context {
            legal_time @2026-09-13;
            decision_time @2026-09-13T09:00:00+05:00;
            knowledge_time @2026-09-13T09:00:00+05:00;
            timezone "Asia/Almaty";
        }
        assert eligible(entity_ref("urn:recipe:b-rules:02:p")); assert special(entity_ref("urn:recipe:b-rules:02:p")); assert restored(entity_ref("urn:recipe:b-rules:02:p"));
    }
    evaluate truth(allowed(entity_ref("urn:recipe:b-rules:02:p")));
    expect truth_status == TRUE_ONLY;
    expect evaluation_status == COMPUTED;
}

last exception removed

test "last exception removed" {
    given {
        context {
            legal_time @2026-09-13;
            decision_time @2026-09-13T09:00:00+05:00;
            knowledge_time @2026-09-13T09:00:00+05:00;
            timezone "Asia/Almaty";
        }
        assert eligible(entity_ref("urn:recipe:b-rules:02:p")); assert special(entity_ref("urn:recipe:b-rules:02:p")); assert restored(entity_ref("urn:recipe:b-rules:02:p"));
    }
    evaluate truth(allowed(entity_ref("urn:recipe:b-rules:02:p")));
    expect truth_status == FALSE_ONLY;
    expect evaluation_status == COMPUTED;
}

same conditions, reversed order

test "same conditions, reversed order" {
    given {
        context {
            legal_time @2026-09-13;
            decision_time @2026-09-13T09:00:00+05:00;
            knowledge_time @2026-09-13T09:00:00+05:00;
            timezone "Asia/Almaty";
        }
        assert eligible(entity_ref("urn:recipe:b-rules:02:p")); assert special(entity_ref("urn:recipe:b-rules:02:p")); assert restored(entity_ref("urn:recipe:b-rules:02:p"));
    }
    evaluate truth(reversed(entity_ref("urn:recipe:b-rules:02:p")));
    expect truth_status == FALSE_ONLY;
    expect evaluation_status == COMPUTED;
}

Counterfactual

Mutation: rule General defeasible → rule General strict; rejection LDC-E4110. Scenes that delete a fragment are marked explicitly in the table.

Boundary

Each exception condition binds p on its own. Independent grounds need an explicit priority scheme, not an arbitrary order of provisos. Reversed is a separate witness of reordering; it does not take part in deriving allowed.

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