Cyclic Agree [BR09] #
[BR09] derive person hierarchy (PH) effects from three independently motivated mechanisms:
- Articulated φ-features: person is decomposed into hierarchical segments — [π] ⊂ [participant] ⊂ [speaker]/[addressee] — each of which can independently enter Agree.
- Feature-relativized locality: a probe segment [uF] only sees goals bearing [F]; a goal lacking [F] is bypassed, leaving an active residue.
- Cyclic expansion: v's probe first Agrees with the IA (cycle I), then with the EA (cycle II). The IA is preferred because cyclicity puts it in the search space first.
The interaction of probe articulation and cyclic Agree derives:
- Agreement displacement: IA agreement bleeds EA agreement when the IA fully checks the probe. When it doesn't, residue reaches the EA.
- Direct/Inverse contexts: Inverse = core probe doesn't Agree with EA (IA fully checks, or EA can't match the residue). Direct = EA Agrees with residue segments.
- Crosslinguistic variation: languages differ in probe articulation — flat [u-3] (no PH sensitivity), partial [u-3-2] (SAP vs 3P), or full [u-3-2-1] (all persons distinguished).
Person Geometries #
Two attested geometries for the innermost feature:
- Standard (1>2>3): [speaker] distinguishes 1st from 2nd. Used by Basque, Georgian ([BR09] Table 2B).
- Addressee (2>1>3): [addressee] distinguishes 2nd from 1st. Used by Nishnaabemwin, Mohawk ([BR09] Table 2C).
Person Licensing and Repair #
The Person-Licensing Condition (PLC) requires every π-feature to be licensed by Agree. In inverse contexts, the EA's π-features are not licensed by the core probe, triggering repair strategies:
- Added probe: an extra probe is inserted on v_II in inverse contexts (Nishnaabemwin, Mohawk, Basque)
- R-Case: the IA receives a special oblique Case (Kashmiri)
Both strategies are derivationally bounded: they occur in all and only inverse contexts.
Integration #
Connects to Phi/Geometry.lean via bridge theorems. The direct/inverse
classification predicts which languages show differential P indexing
(Basque, Georgian fragments).
Sibling mechanisms in Syntax/Minimalism/ #
NestedAgree.lean ([Ama25]) and Long-Distance Agree
([Sza09], Studies/Allotey2021.lean) are sibling Layer-2
patterns. All three address what a probe does beyond its first
operation, but differently:
- Cyclic Agree (this file): single articulated probe with multiple feature segments; cycle II's residue probing expands the domain to reach the EA after the IA partially checks the probe.
- Nested Agree: multiple ordered probes on one head, all forced under maximized matching to target the same goal; each subsequent probe operates on a truncated domain restricted to the first goal's daughters.
- Long-Distance Agree: a single probe relaxes clause-locality across a non-defective C.
The three are conceptually orthogonal — Cyclic addresses articulation, Nested addresses ordering, LDA addresses clause-boundedness. A given construction may instantiate one but not the others.
A single segment in an articulated person feature structure.
Segments are privative features organized in a containment hierarchy. Every person value bears [π]; SAPs additionally bear [participant]; the innermost feature ([speaker] or [addressee]) distinguishes 1st from 2nd person.
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- Minimalist.CyclicAgree.instDecidableEqSegment x✝ y✝ = if h : x✝.ctorIdx = y✝.ctorIdx then isTrue ⋯ else isFalse ⋯
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- Minimalist.CyclicAgree.instDecidableEqGeometry x✝ y✝ = if h : x✝.ctorIdx = y✝.ctorIdx then isTrue ⋯ else isFalse ⋯
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The person specification for a given person value under a geometry.
Returns the list of segments a DP of this person bears.
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- Minimalist.CyclicAgree.personSpec geom Person.third = [Minimalist.CyclicAgree.Segment.pi]
- Minimalist.CyclicAgree.personSpec geom Person.zero = [Minimalist.CyclicAgree.Segment.pi]
- Minimalist.CyclicAgree.personSpec Minimalist.CyclicAgree.Geometry.addressee Person.first = [Minimalist.CyclicAgree.Segment.pi, Minimalist.CyclicAgree.Segment.participant]
- Minimalist.CyclicAgree.personSpec Minimalist.CyclicAgree.Geometry.addressee Person.firstInclusive = [Minimalist.CyclicAgree.Segment.pi, Minimalist.CyclicAgree.Segment.participant]
- Minimalist.CyclicAgree.personSpec Minimalist.CyclicAgree.Geometry.addressee Person.firstExclusive = [Minimalist.CyclicAgree.Segment.pi, Minimalist.CyclicAgree.Segment.participant]
- Minimalist.CyclicAgree.personSpec Minimalist.CyclicAgree.Geometry.standard Person.second = [Minimalist.CyclicAgree.Segment.pi, Minimalist.CyclicAgree.Segment.participant]
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The most specified person under a given geometry.
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An articulated probe: a list of unvalued segments, ordered from outermost (most general) to innermost (most specific).
Languages vary parametrically in probe articulation:
- Flat [u-3]: no PH sensitivity (e.g., Swahili, Abkhaz)
- Partial [u-3-2]: distinguishes SAP from 3P (e.g., Basque, Georgian)
- Full [u-3-2-1]: distinguishes all persons (e.g., Nishnaabemwin, Mohawk)
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Flat probe: [uπ]. Any DP fully matches.
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Partial probe: [uπ, uParticipant]. Distinguishes SAP from 3P. Geometry-independent: [participant] is the same in both geometries.
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Full probe in standard geometry: [uπ, uParticipant, uSpeaker].
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Full probe in addressee geometry: [uπ, uParticipant, uAddressee].
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A language's agreement system: the geometry and characteristic probe.
[BR09] parameterize crosslinguistic variation by two choices: (1) which geometry organizes the innermost feature, and (2) how articulated the probe is. The full probe depends on the geometry (standard uses [speaker], addressee uses [addressee]).
- geometry : Geometry
- probe : Probe.Articulation
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Swahili/Abkhaz: flat probe, no PH sensitivity.
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- Minimalist.CyclicAgree.swahili = { geometry := Minimalist.CyclicAgree.Geometry.standard, probe := Minimalist.CyclicAgree.flatProbe }
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Basque/Georgian: partial probe, standard geometry.
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- Minimalist.CyclicAgree.basque = { geometry := Minimalist.CyclicAgree.Geometry.standard, probe := Minimalist.CyclicAgree.partialProbe }
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Nishnaabemwin/Mohawk: full probe, addressee geometry.
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Active residue: unmatched probe segments after Agree with a goal DP.
Each probe segment that has a corresponding segment in the goal's person specification is deactivated (matched). Segments without a match remain active and can participate in further Agree on the next cycle.
This is the core operation of [BR09]: partial matching of articulated probes drives agreement displacement.
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- Minimalist.CyclicAgree.activeResidue probe goal = List.filter (fun (s : Minimalist.CyclicAgree.Segment) => !goal.contains s) probe
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- Minimalist.CyclicAgree.instDecidableEqController x✝ y✝ = if h : x✝.ctorIdx = y✝.ctorIdx then isTrue ⋯ else isFalse ⋯
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Does the EA Agree with residue segments on cycle II?
Returns true iff the EA matches at least one segment that the
IA left unmatched.
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Determine which argument controls the core agreement slot.
Cycle I: probe Agrees with IA. If residue remains, cycle II: probe Agrees with EA. EA controls iff it matches any residue segment; otherwise IA controls (either it fully checked the probe, or it left residue the EA couldn't match).
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The person value that the core agreement slot realizes.
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Convenience: controller using an AgreementSystem.
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- sys.controller ea ia = Minimalist.CyclicAgree.agreementController sys.geometry sys.probe ea ia
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Convenience: agreement value using an AgreementSystem.
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- sys.value ea ia = Minimalist.CyclicAgree.agreementValue sys.geometry sys.probe ea ia
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Which cycle valued the probe's remaining segments.
[BR09] §3.2: when the probe is valued on two different cycles, the morphological realization can differ. Georgian uses m- (first cycle) vs v- (second cycle) for 1sg agreement; Nishnaabemwin uses -in (1P, cycle II) vs -igw (3P, cycle II) vs -aa (default/cycle I only).
Returns (cycleI, cycleII) — the segments deactivated on each cycle.
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Was the probe valued on two distinct cycles?
True when both the IA (cycle I) and EA (cycle II) matched at least one segment. This is the configuration that creates second-cycle morphological effects in languages like Georgian and Nishnaabemwin.
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- Minimalist.CyclicAgree.hasSecondCycleEffect geom probe ea ia = match Minimalist.CyclicAgree.cycleSegments geom probe ea ia with | (c1, c2) => !List.isEmpty c1 && !List.isEmpty c2
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Inverse context: the core π-probe on v does NOT Agree with the EA.
This occurs when either (a) the IA fully checks the probe, leaving no residue, or (b) residue exists but the EA cannot match any of it. Inverse contexts trigger PLC violations on the EA's π-features, requiring repair strategies (added probe or R-Case).
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- Minimalist.CyclicAgree.isInverseContext geom probe ea ia = !Minimalist.CyclicAgree.eaAgrees geom probe ea ia
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Direct context: the EA Agrees with at least one residue segment.
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- Minimalist.CyclicAgree.isDirectContext geom probe ea ia = Minimalist.CyclicAgree.eaAgrees geom probe ea ia
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Convenience: inverse using an AgreementSystem.
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- sys.isInverse ea ia = Minimalist.CyclicAgree.isInverseContext sys.geometry sys.probe ea ia
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The Person-Licensing Condition (PLC).
[BR09] eq. (13): "A π-feature [F] must be licensed by Agree of some segment in a feature structure of which [F] is a subset."
In inverse contexts, the EA's π-features are not licensed by the core probe (because the probe either has no residue or residue the EA can't match). This drives repair strategies.
Returns true if the EA is person-licensed (its π-features were
checked by the core probe on cycle II).
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- Minimalist.CyclicAgree.eaIsLicensed geom probe ea ia = Minimalist.CyclicAgree.eaAgrees geom probe ea ia
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PLC violation: EA is NOT person-licensed. Exactly characterizes inverse contexts — this is the paper's key insight connecting syntactic derivation to morphological repair.
Grounding in relativized search (Probe/Basic.lean) #
An articulated probe is a family of flat relativized searches, one per segment, over the cyclically ordered token list: B&R's segments match independently, so cyclic expansion at the whole-probe level is first-visible-goal search at the per-segment level. The residue-based definitions above remain definitional — they are the paper's mechanism; the factorization is a result about it.
Cf. Studies/BejarRezac2003.lean for the 2003 precursor's
second-cycle repair: formally distinct mechanisms — 2003 varies the
goal order under one probe; cyclic expansion here varies the
relativization (per segment) over one order.
The two arguments as φ-bearing goal tokens, in cyclic search order: the IA precedes the EA (cycle I before cycle II).
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Visibility of an argument token to a probe segment s: the
argument's person specification bears s (feature-relativized
locality).
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- Minimalist.CyclicAgree.segVisible geom s t = (Minimalist.CyclicAgree.personSpec geom t.2).contains s
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A probe segment as a Probe over argument tokens.
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The goal a single probe segment Agrees with: the first argument in
cyclic order whose specification bears the segment — a flat
relativized Probe.search.
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- Minimalist.CyclicAgree.segmentGoal geom ea ia s = (Minimalist.CyclicAgree.segProbe geom s).search (Minimalist.CyclicAgree.goalTokens ea ia)
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A segment finds the EA token iff the IA bypasses it (leaving it as active residue) and the EA bears it — cycle-II Agree.
A segment finds the IA token iff the IA bears it — cycle-I Agree.
Existential characterization of the residue-based eaAgrees.
Main bridge: the EA is person-licensed (eaIsLicensed) iff some
probe segment's flat relativized search (Probe.Licensed) over
the cyclically ordered token list finds the EA token.
PLC violation ↔ no segment's search licenses the EA token — the inverse-context characterization restated through the search substrate.
Cycle decomposition through the search: cycle-I segments are those
whose search finds the IA token; cycle-II segments those whose
search finds the EA token. Second-cycle effects also factor through
Probe.search.
Repair strategies for PLC violations in inverse contexts.
[BR09] §4 identifies two strategies:
addedProbe: an extra probe is inserted on v_II, creating an additional agreement slot for the EA (Nishnaabemwin, Mohawk, Basque)rCase: the IA receives a special oblique Case distinct from the regular v-assigned Case (Kashmiri)
- addedProbe : RepairStrategy
- rCase : RepairStrategy
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- Minimalist.CyclicAgree.instDecidableEqRepairStrategy x✝ y✝ = if h : x✝.ctorIdx = y✝.ctorIdx then isTrue ⋯ else isFalse ⋯
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Does a given EA→IA combination require repair under this system?
Repair is needed iff the context is inverse.
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- Minimalist.CyclicAgree.needsRepair sys ea ia = sys.isInverse ea ia
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In the standard geometry, a person value has [participant] as a segment
iff DecomposedPerson.hasParticipant is true.
In the standard geometry, 3rd person has exactly one segment ([π]).
Segment count reflects the person hierarchy: 1st (3 segments) > 2nd (2) > 3rd (1) in standard geometry.
Entailment: more specified persons' segments are supersets.
Flat probe: IA always fully checks the probe, regardless of person.
Flat probe: IA always controls — no PH effects.
Flat probe: all contexts are inverse (no EA agreement).
Partial probe: same behavior in both geometries, since [participant] is geometry-independent.
Basque: 3→1 = 1 (IA controls, inverse).
Basque: 2→1 = 1 (IA controls, inverse).
Basque: 1→2 = 2 (IA controls, inverse).
Basque: 3→2 = 2 (IA controls, inverse).
Basque: 1→3 = 1 (EA controls, direct).
Basque: 2→3 = 2 (EA controls, direct).
Basque: 3→3 = 3 (IA controls, inverse — residue [uParticipant] unmatched by either argument).
Basque: SAP IA → inverse context (agreement displacement to IA).
Basque: 3P IA + SAP EA → direct context (EA controls).
Basque: 3P IA + 3P EA → inverse (neither fully checks).
Nishnaabemwin: 3→2 = 2 (IA controls, inverse — IA fully checks).
Nishnaabemwin: 1→2 = 2 (IA controls, inverse — IA fully checks).
Nishnaabemwin: 3→1 = 1 (IA controls, inverse — EA can't match residue).
Nishnaabemwin: 2→1 = 2 (EA controls, direct — EA matches [uAddressee]).
Nishnaabemwin: 1→3 = 1 (EA controls, direct).
Nishnaabemwin: 2→3 = 2 (EA controls, direct).
Nishnaabemwin: 3→3 = 3 (IA controls, inverse — residue [uParticipant, uAddressee] unmatched by 3P EA).
Nishnaabemwin: 2P IA → always inverse (2nd is most specified).
Nishnaabemwin: 3P IA with SAP EA → direct.
Nishnaabemwin: 3→1 is inverse despite residue, because EA (3P) can't match [addressee].
Nishnaabemwin: 3→3 is inverse.
Georgian second-cycle effect: 1sg agreement is m- when valued on cycle I (IA=1, any EA), but v- when valued on cycle II (EA=1, IA=3).
Georgian: when IA is SAP, no second cycle (IA fully checks).
Nishnaabemwin: 2→1 has a second-cycle effect (IA checks [π,participant], EA checks [addressee] on cycle II).
Nishnaabemwin: the second cycle in 2→1 values exactly [addressee].
When EA and IA have the same person, IA always controls (the EA contributes nothing new — every segment it could match was already matched by the identical IA).
The proof proceeds by showing that activeResidue is idempotent
when applied with the same goal: if some segments survive matching
against personSpec(p), applying the same filter again removes nothing,
so eaAgrees returns false.
The most specified person always controls against 3P (standard).
The most specified person always controls against 3P (addressee).
The direct/inverse split exhaustively partitions the paradigm: every EA→IA combination is either direct or inverse, never both.
In a partial-probe language like Basque/Georgian, object (P) agreement is person-conditioned: the object controls agreement iff the context is direct (EA > IA on the person hierarchy). This predicts that SAP objects trigger agreement displacement to EA, while 3P objects don't.
Formally: for a fixed 3P EA (the "subject" in a canonical transitive), a SAP IA triggers direct context (EA controls → "no P indexing"), but this is backwards from the traditional description. Let's think about it from the P indexing perspective:
In Basque, the agreement slot tracks the controller. When IA is SAP, IA controls (inverse) — the agreement tracks IA, reflecting the object. When IA is 3P, EA controls (direct) — agreement tracks EA, not the object.
So pIsIndexed ↔ the IA controls (the agreement slot shows the
object's features) ↔ inverse context.
3P IA yields direct context when EA is SAP — the agreement slot tracks the EA, not the (3P) object.
Differential P indexing prediction: the SAP/3P split in object
agreement (Basque pIsIndexed, Georgian pIsIndexed) is exactly
the inverse/direct split of the partial probe.
An object (IA) is "indexed" when the core agreement slot tracks the IA's person features, which happens iff the context is inverse (IA controls). SAP IAs always produce inverse contexts; 3P IAs produce direct contexts (when EA is SAP).
This theorem proves the key direction: SAP IA → inverse (indexed).
Count inverse contexts in a 3×3 paradigm.
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Swahili (flat): all 9 cells are inverse (no PH sensitivity).
Basque (partial): 7 inverse, 2 direct (only SAP EA + 3P IA).
Nishnaabemwin (full): 6 inverse, 3 direct.
More articulated probes yield more direct contexts.