Drubea Prosodic Fragment

@cite{lionnet-2025}

Lexical register specifications for Drubea [ŋaa ⁺ⁿɖuᵐbea] (Glottocode: dumb1241), an Oceanic language of New Caledonia spoken by approximately 1,000 people in Unya on the east coast and Paita on the west coast of Grande Terre.

The word-prosodic system consists of an underlying binary contrast between registerless and downstepped register-bearing units (RBUs), with the mora as the RBU. There are no tone features.

Data from @cite{lionnet-2025}, building on @cite{rivierre-1973} and @cite{shintani-paita-1990b}.

inductive Fragments.Drubea.Prosody.StemPattern : Type

The three native stem-level register patterns in Drubea (@cite{lionnet-2025}: Table 2, §4.2).

The contrast is between downstepped and registerless RBUs. Each stem contains at most one l feature (culminativity). The l feature associates with the leftmost mora of a syllable (Table 3).

• registerless : StemPattern
• σ1_downstepped : StemPattern
• σ2_downstepped : StemPattern

@[implicit_reducible]

instance Fragments.Drubea.Prosody.instDecidableEqStemPattern : DecidableEq StemPattern

Equations

• Fragments.Drubea.Prosody.instDecidableEqStemPattern x✝ y✝ = if h : x✝.ctorIdx = y✝.ctorIdx then isTrue ⋯ else isFalse ⋯

@[implicit_reducible]

instance Fragments.Drubea.Prosody.instReprStemPattern : Repr StemPattern

Equations

• Fragments.Drubea.Prosody.instReprStemPattern = { reprPrec := Fragments.Drubea.Prosody.instReprStemPattern.repr }

def Fragments.Drubea.Prosody.instReprStemPattern.repr : StemPattern → ℕ → Std.Format

Equations

• One or more equations did not get rendered due to their size.

def Fragments.Drubea.Prosody.StemPattern.toSpecs (p : StemPattern) (nMorae : ℕ) : List Phonology.Autosegmental.RegisterTier.TRN

Expand a stem pattern to mora-level register specifications.

nMorae is the total mora count of the stem. The three patterns map to:

• ∅: [∅, ∅, …]
• l: [l, ∅, …]
• ∅l: [∅, l, ∅, …]

Equations

• One or more equations did not get rendered due to their size.
• Fragments.Drubea.Prosody.StemPattern.registerless.toSpecs nMorae = List.replicate nMorae Phonology.Autosegmental.RegisterTier.TRN.empty

structure Fragments.Drubea.Prosody.StemEntry : Type

A Drubea stem with its prosodic specification.

• form : String
• gloss : String
• pattern : StemPattern
• nMorae : ℕ

def Fragments.Drubea.Prosody.instReprStemEntry.repr : StemEntry → ℕ → Std.Format

Equations

• One or more equations did not get rendered due to their size.

@[implicit_reducible]

instance Fragments.Drubea.Prosody.instReprStemEntry : Repr StemEntry

Equations

• Fragments.Drubea.Prosody.instReprStemEntry = { reprPrec := Fragments.Drubea.Prosody.instReprStemEntry.repr }

def Fragments.Drubea.Prosody.StemEntry.specs (e : StemEntry) : List Phonology.Autosegmental.RegisterTier.TRN

Register specification derived from a stem entry.

Equations

• e.specs = e.pattern.toSpecs e.nMorae

def Fragments.Drubea.Prosody.monoMinimalPairs : List (StemEntry × StemEntry)

Monosyllabic CV minimal pairs: segmentally identical stems contrasting only in register (@cite{lionnet-2025}: ex. 4).

Each pair shares the same segmental form; the prosodic contrast is purely a matter of the presence vs. absence of a downstep feature.

Equations

• One or more equations did not get rendered due to their size.

def Fragments.Drubea.Prosody.cvPlusVTriplets : List (StemEntry × StemEntry × StemEntry)

CV⁺V minimal triplets: three-way contrast on bimoraic monosyllables (@cite{lionnet-2025}: ex. 45).

These triplets demonstrate that the RBU is the mora, not the syllable: within a single bimoraic syllable CVV, the downstep can target either the first mora (⁺CVV) or the second (CV⁺V).

Equations

• One or more equations did not get rendered due to their size.

def Fragments.Drubea.Prosody.disyllableExamples : List StemEntry

Disyllabic CV.CV stems illustrating all three register types (@cite{lionnet-2025}: ex. 34).

Equations

• One or more equations did not get rendered due to their size.

def Fragments.Drubea.Prosody.allStems : List StemEntry

All stems in the fragment.

Equations

• One or more equations did not get rendered due to their size.

theorem Fragments.Drubea.Prosody.mono_pairs_same_form : (monoMinimalPairs.all fun (x : StemEntry × StemEntry) => match x with | (a, b) => a.form == b.form) = true

Every minimal pair shares the same segmental form — the contrast is purely prosodic (register), not segmental.

inductive Fragments.Drubea.Prosody.BoundaryFeature : Type

Boundary register features for utterance-final prosody (@cite{lionnet-2025} §4.8).

• h%: utterance-final raising (Drubea)
• l%: utterance-final lowering (Numèè)

• h_pct : BoundaryFeature
• l_pct : BoundaryFeature

@[implicit_reducible]

instance Fragments.Drubea.Prosody.instDecidableEqBoundaryFeature : DecidableEq BoundaryFeature

Equations

• Fragments.Drubea.Prosody.instDecidableEqBoundaryFeature x✝ y✝ = if h : x✝.ctorIdx = y✝.ctorIdx then isTrue ⋯ else isFalse ⋯

@[implicit_reducible]

instance Fragments.Drubea.Prosody.instReprBoundaryFeature : Repr BoundaryFeature

Equations

• Fragments.Drubea.Prosody.instReprBoundaryFeature = { reprPrec := Fragments.Drubea.Prosody.instReprBoundaryFeature.repr }

def Fragments.Drubea.Prosody.instReprBoundaryFeature.repr : BoundaryFeature → ℕ → Std.Format

Equations

• One or more equations did not get rendered due to their size.

def Fragments.Drubea.Prosody.applyBoundary (specs : List Phonology.Autosegmental.RegisterTier.TRN) (boundary : BoundaryFeature) : List Phonology.Autosegmental.RegisterTier.TRN

Apply a boundary feature to the final registerless syllable.

Simplified model: replaces the last registerless RBU with the boundary feature. Does not model spreading of h%, the mora-weight restriction on l%, or the preceding-context condition (Numèè l% only applies after registerless syllables; @cite{lionnet-2025} §§3.3–3.4, §4.8).

Equations

• Fragments.Drubea.Prosody.applyBoundary specs Fragments.Drubea.Prosody.BoundaryFeature.h_pct = Fragments.Drubea.Prosody.applyBoundary.go Phonology.Autosegmental.RegisterTier.TRN.upstep specs
• Fragments.Drubea.Prosody.applyBoundary specs Fragments.Drubea.Prosody.BoundaryFeature.l_pct = Fragments.Drubea.Prosody.applyBoundary.go Phonology.Autosegmental.RegisterTier.TRN.downstep specs

def Fragments.Drubea.Prosody.applyBoundary.go (feature : Phonology.Autosegmental.RegisterTier.TRN) : List Phonology.Autosegmental.RegisterTier.TRN → List Phonology.Autosegmental.RegisterTier.TRN

Equations

• Fragments.Drubea.Prosody.applyBoundary.go feature [] = []
• Fragments.Drubea.Prosody.applyBoundary.go feature [{ upper := none, raised := none }] = [feature]
• Fragments.Drubea.Prosody.applyBoundary.go feature (x_1 :: rest) = x_1 :: Fragments.Drubea.Prosody.applyBoundary.go feature rest

def Fragments.Drubea.Prosody.wordProsodicType : Phonology.Autosegmental.RegisterTier.WordProsodicType

Drubea is a register-based tone system (@cite{lionnet-2025} §6.2).

Equations

• Fragments.Drubea.Prosody.wordProsodicType = Phonology.Autosegmental.RegisterTier.WordProsodicType.registerBased

def Fragments.Drubea.Prosody.tbuKind : Phonology.Autosegmental.RegisterTier.TBUKind

The register-bearing unit in Drubea is the mora (@cite{lionnet-2025} §4.2).

Equations

• Fragments.Drubea.Prosody.tbuKind = Phonology.Autosegmental.RegisterTier.TBUKind.mora

def Fragments.Drubea.Prosody.drubeaBoundary : BoundaryFeature

Drubea uses utterance-final raising (h%).

Equations

• Fragments.Drubea.Prosody.drubeaBoundary = Fragments.Drubea.Prosody.BoundaryFeature.h_pct

def Fragments.Drubea.Prosody.numeeBoundary : BoundaryFeature

Numèè uses utterance-final lowering (l%).

Equations

• Fragments.Drubea.Prosody.numeeBoundary = Fragments.Drubea.Prosody.BoundaryFeature.l_pct