Module likeliness 

Likeliness — a qualitative, ordinal calculus of expectation (Vector Semantics §4.2; Kornai’s “naive” inference). The third uncertainty modality, built as its own thing rather than folded into defeasible/fuzzy.

Timothy, 2026-06-27: “I’m undecided [whether it folds], which suggests it should be done as a new modality.” Indecision about the fold is itself the signal that this is a distinct calculus — forcing it into an existing modality would distort both.

Why it is genuinely distinct

• Not crate::modalities::probabilistic (continuous [0,1], Kolmogorov/Bayes): likeliness is ordinal and non-additive — P(x) and P(¬x) need not sum to a constant, and there is no normalisation. It expresses how expected a proposition is, qualitatively.
• Not crate::modalities::fuzzy (continuous [0,1] set-membership, t-norm): likeliness is graded belief/expectation over propositions, not degree of set-membership.
• Adjacent to crate::modalities::defeasible (defaults) but distinct: defeasible resolves a crisp conclusion by rule priority/defeaters; likeliness carries a graded degree on the conclusion and composes it.

The calculus

Likeliness lives on a symmetric 7-level ordinal scale centred on Even. The logical operators (algebra) form a Kleene / De Morgan algebra: not is the order-reversing involution, and is the meet (weakest link), or the join (best alternative). Crucially or(l, not l) need not be Certain and and(l, not l) need not be Impossible — no excluded middle, no contradiction collapse — which is exactly the non-probabilistic, defeasible character. On top sit the naive inference rules (inference): weakest-link modus ponens, chain attenuation, and defeasible revision. Kernel-class ElementwiseMap (trivial CPU; no GPU path, §13).

Re-exports

pub use algebra::and;

pub use algebra::combine_premises;

pub use algebra::combine_routes;

pub use algebra::not;

pub use algebra::or;

pub use inference::attenuate;

pub use inference::infer_chain;

pub use inference::modus_ponens;

pub use inference::rebut;

pub use inference::revise;

Modules

algebra

The Kleene / De Morgan lattice on the likeliness scale. These are the logical connectives of the calculus; the non-probabilistic character lives here (no excluded middle, no contradiction collapse).

inference

Naive inference and defeasible revision over likeliness — the “specific update rule” half of the calculus. Built on the super::algebra lattice so the laws are inherited (reuse, not a parallel set of rules).

Enums

Likeliness

An ordinal degree of expectation. Stored so self as i8 is the signed level in [-3, +3], with Even = 0 the point of no information.