Toba Batak Extraction Restriction @cite{erlewine-2018}

Theory-neutral empirical data on the extraction restriction in Toba Batak: only the pivot can undergo Ā-movement (wh-movement, relativization, clefting).

Key Empirical Findings

1. Pivot-only extraction: Only the pivot argument can be Ā-extracted. All other arguments are trapped (§2).
2. Voice determines pivot: Actor Voice → agent is pivot; Object Voice → patient is pivot (§2.1).
3. Voice symmetry: AV makes the agent extractable but not the patient; OV makes the patient extractable but not the agent.
4. Long-distance extraction: The extracted element must be the pivot of the most deeply embedded clause, and intermediate clauses show extraction morphology (§4).

Cross-Linguistic Context

Toba Batak's extraction restriction contrasts with:

• Tagalog/Seediq (Austronesian): Philippine-style voice/Case determines extraction via agreement morphology — a voice-as-case system. @cite{erlewine-2018} argues TB is NOT this type.
• Mam (Mayan): Extraction is unrestricted, but oblique extraction triggers a dedicated morpheme (=(y)a') as an Agree reflex on Voice⁰.
• English: No extraction restriction; gap strategy.

TB and Tagalog are both Austronesian and both use voice morphology, but the mechanism differs: Tagalog has voice-as-Case, while TB has predicate fronting + nominal licensing (DPs in Spec,CP lack a Case licensor). Mam (Mayan) shows a third pattern: unrestricted extraction with morphological reflexes of Agree.

theorem Phenomena.FillerGap.TobaBatak.extraction_data_count : Fragments.TobaBatak.extractionData.length = 8

theorem Phenomena.FillerGap.TobaBatak.av_agent_grammatical : Fragments.TobaBatak.avAgentExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.grammatical ∧ Fragments.TobaBatak.avAgentExtraction.extractsPivot = true

AV + agent (pivot): grammatical.

theorem Phenomena.FillerGap.TobaBatak.av_patient_ungrammatical : Fragments.TobaBatak.avPatientExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.ungrammatical ∧ Fragments.TobaBatak.avPatientExtraction.extractsPivot = false

AV + patient (non-pivot): ungrammatical.

theorem Phenomena.FillerGap.TobaBatak.av_oblique_ungrammatical : Fragments.TobaBatak.avObliqueExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.ungrammatical ∧ Fragments.TobaBatak.avObliqueExtraction.extractsPivot = false

AV + oblique (non-pivot): ungrammatical.

theorem Phenomena.FillerGap.TobaBatak.ov_patient_grammatical : Fragments.TobaBatak.ovPatientExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.grammatical ∧ Fragments.TobaBatak.ovPatientExtraction.extractsPivot = true

OV + patient (pivot): grammatical.

theorem Phenomena.FillerGap.TobaBatak.ov_agent_ungrammatical : Fragments.TobaBatak.ovAgentExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.ungrammatical ∧ Fragments.TobaBatak.ovAgentExtraction.extractsPivot = false

OV + agent (non-pivot): ungrammatical.

theorem Phenomena.FillerGap.TobaBatak.ov_oblique_ungrammatical : Fragments.TobaBatak.ovObliqueExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.ungrammatical ∧ Fragments.TobaBatak.ovObliqueExtraction.extractsPivot = false

OV + oblique (non-pivot): ungrammatical.

theorem Phenomena.FillerGap.TobaBatak.av_adjunct_grammatical : Fragments.TobaBatak.avAdjunctExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.grammatical

AV + adjunct: grammatical (adjuncts don't need Case).

theorem Phenomena.FillerGap.TobaBatak.ov_adjunct_grammatical : Fragments.TobaBatak.ovAdjunctExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.grammatical

OV + adjunct: grammatical (adjuncts don't need Case).

theorem Phenomena.FillerGap.TobaBatak.dp_extraction_iff_pivot : (Fragments.TobaBatak.extractionData.all fun (d : Fragments.TobaBatak.ExtractionDatum) => match d.extracted with | Interfaces.Extractee.dpArg a => d.extractsPivot == (d.judgment == Fragments.TobaBatak.ExtractionJudgment.grammatical) | Interfaces.Extractee.adjunct => true) = true

For DP arguments: extraction is grammatical iff the extracted element is the pivot for the given voice (§2).

theorem Phenomena.FillerGap.TobaBatak.adjunct_always_grammatical : (Fragments.TobaBatak.extractionData.all fun (d : Fragments.TobaBatak.ExtractionDatum) => match d.extracted with | Interfaces.Extractee.adjunct => d.judgment == Fragments.TobaBatak.ExtractionJudgment.grammatical | Interfaces.Extractee.dpArg a => true) = true

For non-DP adjuncts: extraction is always grammatical regardless of voice, because adjuncts don't need Case licensing (§4.3).

theorem Phenomena.FillerGap.TobaBatak.voice_symmetry : Fragments.TobaBatak.avAgentExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.grammatical ∧ Fragments.TobaBatak.ovPatientExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.grammatical ∧ Fragments.TobaBatak.avPatientExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.ungrammatical ∧ Fragments.TobaBatak.ovAgentExtraction.judgment = Fragments.TobaBatak.ExtractionJudgment.ungrammatical

Voice symmetry: AV and OV are mirror images — each makes exactly one argument extractable (the pivot) and blocks all others.

theorem Phenomena.FillerGap.TobaBatak.tb_strategy : Fragments.TobaBatak.tbExtractionProfile.strategy = Interfaces.ExtractionMarkingStrategy.structuralRestriction

TB uses structural restriction, not dedicated morpheme or voice alternation in the Tagalog sense.

theorem Phenomena.FillerGap.TobaBatak.tb_distinguishes : Fragments.TobaBatak.tbExtractionProfile.distinguishesPosition = true

TB distinguishes extracted positions via voice (which role is pivot).

Extraction data → ExtractionProfile → AH → Relativization

Connects three independent data sources through the AH bridge:

1. Individual extraction datums (from @cite{erlewine-2018})
2. The ExtractionProfile summary (markedPositions)
3. RelClauseMarkers (from @cite{keenan-comrie-1977})

If any link is wrong — e.g., listing .directObject as extractable when relativization markers don't cover DO — the chain breaks.

Note: the extraction data uses ArgumentRole (agent, patient) while the ExtractionProfile and AH use ExtractionTarget (subject, directObject). Voice promotion means the patient's default position is DO, but its surface extraction position is always subject (the pivot). The chain must go through the ExtractionProfile, which encodes this fact.

theorem Phenomena.FillerGap.TobaBatak.profile_matches_data : (Fragments.TobaBatak.tbExtractionProfile.markedPositions.all fun (pos : Interfaces.ExtractionTarget) => Fragments.TobaBatak.extractionData.any fun (d : Fragments.TobaBatak.ExtractionDatum) => match d.extracted with | Interfaces.Extractee.dpArg role => decide ((role.defaultPosition == pos) = true ∧ (d.judgment == Fragments.TobaBatak.ExtractionJudgment.grammatical) = true ∧ d.extractsPivot = true) | Interfaces.Extractee.adjunct => false) = true

Link 1→2: The ExtractionProfile's marked positions are exactly the positions for which some voice makes a DP argument grammatically extractable. Only .subject qualifies (the pivot position).

theorem Phenomena.FillerGap.TobaBatak.extractable_positions_are_relativizable : (Fragments.TobaBatak.tbExtractionProfile.markedPositions.all fun (et : Interfaces.ExtractionTarget) => have ahPos := Core.extractionTargetToAH et; Fragments.TobaBatak.relMarkers.any fun (x : Core.RelClauseMarker) => x.covers ahPos) = true

Link 2→3: Every extractable position (ExtractionTarget) maps to an AH position that is covered by some Toba Batak relativization marker. Would have failed with the old [.subject, .directObject] because .directObject maps to AHPosition.directObject, which no marker covers.

theorem Phenomena.FillerGap.TobaBatak.extraction_profile_relativization_chain : (Fragments.TobaBatak.extractionData.all fun (d : Fragments.TobaBatak.ExtractionDatum) => match d.extracted with | Interfaces.Extractee.dpArg a => d.extractsPivot == (d.judgment == Fragments.TobaBatak.ExtractionJudgment.grammatical) | Interfaces.Extractee.adjunct => true) = true ∧ Fragments.TobaBatak.tbExtractionProfile.marks Interfaces.ExtractionTarget.subject = true ∧ (Fragments.TobaBatak.tbExtractionProfile.markedPositions.all fun (et : Interfaces.ExtractionTarget) => have ahPos := Core.extractionTargetToAH et; Fragments.TobaBatak.relMarkers.any fun (x : Core.RelClauseMarker) => x.covers ahPos) = true

Full chain (all three links as a single conjunction): (1) every grammatical DP extraction extracts the pivot, (2) the pivot position (subject) is in markedPositions, and (3) every marked position maps to a relativizable AH position. Connects @cite{erlewine-2018}'s extraction data through the ExtractionProfile to @cite{keenan-comrie-1977}'s markers.