@cite{storme-2026}: Systemic Constraints in MaxEnt Grammars #
@cite{storme-2026}
Replication of @cite{storme-2026} "A Method to Evaluate Systemic Constraints in Probabilistic Grammars" (Linguistic Inquiry 57(1)).
Key idea #
Standard MaxEnt grammars evaluate each input→output mapping independently. Storme shows how to incorporate systemic constraints — constraints that evaluate sets of mappings jointly. The running example is *HOMOPHONY: a constraint penalizing output tuples where distinct inputs receive identical surface forms.
Persian hiatus resolution #
The case study is Persian vowel hiatus between /æ/ and /ɑ/. Classical faithfulness (MAX, IDENT) and markedness (*VV, DEP) constraints predict symmetric treatment of /æ.ɑ/ vs. /ɑ.æ/ — deletion of V1 vs. V2 should be equally probable in both. But Storme argues that *HOMOPHONY breaks this symmetry: the grammar prefers output tuples where distinct inputs produce distinct surface forms.
Formalization #
We instantiate MaxEntGrammar with the Persian hiatus domain from
Fragments.Farsi.Phonology, define the classical and systemic constraints,
and verify the key prediction: homophony avoidance breaks the symmetry.
Constraints #
Following standard OT/MaxEnt constraint families:
- MAX (faithfulness): penalizes deletion (1 violation per deleted segment)
- DEP (faithfulness): penalizes epenthesis (1 violation per inserted segment)
- *VV (markedness): penalizes vowel hiatus in the output
- IDENT (faithfulness): penalizes feature change (coalescence)
- *HOMOPHONY (systemic): penalizes identical outputs for distinct inputs
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MAX: penalizes deletion. 1 violation for deleteV1 or deleteV2, 0 otherwise.
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DEP: penalizes epenthesis. 1 violation for epenthesis, 0 otherwise.
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*VV: markedness constraint penalizing vowel hiatus. 1 violation for faithful (hiatus preserved), 0 for all repairs.
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IDENT: penalizes coalescence (feature change). 1 violation for coalescence, 0 otherwise.
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The classical constraint set for Persian hiatus.
Note: weights are illustrative (chosen to make epenthesis the classical winner), not fitted to Storme's experimental data. The qualitative predictions (symmetry, symmetry-breaking) hold for any positive weights since they depend on constraint structure, not specific weight values.
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Harmony scores are symmetric across mirror-image inputs: H(ae.ah, deleteV1) = H(ah.ae, deleteV1) under classical constraints alone, because classical constraints only look at output structure.
Concrete score verification: deletion costs -2 (MAX weight 2, 1 violation), epenthesis costs -1 (DEP weight 1), faithful costs -3 (*VV weight 3), coalescence costs -2 (IDENT weight 2).
The four hiatus inputs indexed by Fin 4.
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- Phenomena.PhonologicalAlternation.Studies.Storme2026.inputsIndexed ⟨0, isLt⟩ = Fragments.Farsi.Phonology.HiatusInput.ae_ae
- Phenomena.PhonologicalAlternation.Studies.Storme2026.inputsIndexed ⟨1, isLt⟩ = Fragments.Farsi.Phonology.HiatusInput.ae_ah
- Phenomena.PhonologicalAlternation.Studies.Storme2026.inputsIndexed ⟨2, isLt⟩ = Fragments.Farsi.Phonology.HiatusInput.ah_ae
- Phenomena.PhonologicalAlternation.Studies.Storme2026.inputsIndexed ⟨3, isLt⟩ = Fragments.Farsi.Phonology.HiatusInput.ah_ah
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*HOMOPHONY for the Persian hiatus paradigm: penalizes output tuples where distinct inputs produce identical outputs.
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Joint harmony score for a complete output tuple, combining classical per-mapping scores with the systemic *HOMOPHONY penalty.
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An output tuple where the mirror-image inputs /æ.ɑ/ and /ɑ.æ/ use different repair strategies (deleteV1 vs deleteV2). Both still surface as [ɑ], so homophony remains at those positions — but the tuple has fewer *HOMOPHONY violations overall than the uniform-strategy tuple.
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- Phenomena.PhonologicalAlternation.Studies.Storme2026.diverseTuple ⟨0, isLt⟩ = Fragments.Farsi.Phonology.HiatusOutput.deleteV1
- Phenomena.PhonologicalAlternation.Studies.Storme2026.diverseTuple ⟨1, isLt⟩ = Fragments.Farsi.Phonology.HiatusOutput.deleteV1
- Phenomena.PhonologicalAlternation.Studies.Storme2026.diverseTuple ⟨2, isLt⟩ = Fragments.Farsi.Phonology.HiatusOutput.deleteV2
- Phenomena.PhonologicalAlternation.Studies.Storme2026.diverseTuple ⟨3, isLt⟩ = Fragments.Farsi.Phonology.HiatusOutput.deleteV1
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A homophonous tuple: both mirror-image inputs use the same strategy.
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- Phenomena.PhonologicalAlternation.Studies.Storme2026.homophonousTuple ⟨0, isLt⟩ = Fragments.Farsi.Phonology.HiatusOutput.deleteV1
- Phenomena.PhonologicalAlternation.Studies.Storme2026.homophonousTuple ⟨1, isLt⟩ = Fragments.Farsi.Phonology.HiatusOutput.deleteV1
- Phenomena.PhonologicalAlternation.Studies.Storme2026.homophonousTuple ⟨2, isLt⟩ = Fragments.Farsi.Phonology.HiatusOutput.deleteV1
- Phenomena.PhonologicalAlternation.Studies.Storme2026.homophonousTuple ⟨3, isLt⟩ = Fragments.Farsi.Phonology.HiatusOutput.deleteV1
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Concrete violation counts:
- homophonousTuple: all 4 positions use deleteV1 → C(4,2) = 6 collisions
- diverseTuple: 3 positions use deleteV1, 1 uses deleteV2 → 3 collisions
*HOMOPHONY incurs more violations on the homophonous tuple than on the diverse tuple. This is the core mechanism by which systemic constraints break symmetry.
The diverse tuple has at least as high joint harmony as the homophonous tuple, because it incurs fewer *HOMOPHONY violations while having the same classical constraint violations.
Classical constraints alone assign the same score to deleteV1 for /æ.ɑ/ and /ɑ.æ/ — the grammar cannot distinguish mirror-image inputs at the individual mapping level. (Restated from §2 for contrast with the non-separability result below.)
Under *HOMOPHONY, the joint distribution over all four mappings is not a product of independent per-mapping distributions. The marginal probability of a specific output for /æ.ɑ/ depends on what outputs are chosen for the other inputs — this is the core mechanism by which systemic constraints influence individual mapping probabilities.
This theorem verifies that the joint score is not additively separable (i.e., there exist tuples f, g agreeing on position 1 but differing in joint score minus the classical score at position 1).