Documentation

Linglib.Syntax.Minimalist.Agree.Cyclic

Cyclic Agree [BR09] #

[BR09] derive person hierarchy (PH) effects from three independently motivated mechanisms:

  1. Articulated φ-features: person is decomposed into hierarchical segments — [π] ⊂ [participant] ⊂ [speaker]/[addressee] — each of which can independently enter Agree.
  2. Feature-relativized locality: a probe segment [uF] only sees goals bearing [F]; a goal lacking [F] is bypassed, leaving an active residue.
  3. 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:

Person Geometries #

Two attested geometries for the innermost feature:

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:

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:

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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      Which feature distinguishes 1st from 2nd person.

      • standard: [speaker] distinguishes 1st (Basque, Georgian)
      • addressee: [addressee] distinguishes 2nd (Nishnaabemwin, Mohawk)
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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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            Partial probe: [uπ, uParticipant]. Distinguishes SAP from 3P. Geometry-independent: [participant] is the same in both geometries.

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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]).

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                    Basque/Georgian: partial probe, standard 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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                        Which argument controls the core agreement slot.

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                            def Minimalist.CyclicAgree.eaAgrees (geom : Geometry) (probe : Probe.Articulation) (ea ia : Person) :
                            Bool

                            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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                                    Convenience: agreement value using an AgreementSystem.

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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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                                          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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                                            Direct context: the EA Agrees with at least one residue segment.

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                                              Convenience: inverse using an AgreementSystem.

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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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                                                  theorem Minimalist.CyclicAgree.plc_violation_iff_inverse (geom : Geometry) (probe : Probe.Articulation) (ea ia : Person) :
                                                  eaIsLicensed geom probe ea ia = false isInverseContext geom probe ea ia = true

                                                  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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                                                      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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                                                          theorem Minimalist.CyclicAgree.segmentGoal_eq_ea_iff (geom : Geometry) (ea ia : Person) (s : Segment) :
                                                          segmentGoal geom ea ia s = some (Controller.ea, ea) (personSpec geom ia).contains s = false (personSpec geom ea).contains s = true

                                                          A segment finds the EA token iff the IA bypasses it (leaving it as active residue) and the EA bears it — cycle-II Agree.

                                                          theorem Minimalist.CyclicAgree.segmentGoal_eq_ia_iff (geom : Geometry) (ea ia : Person) (s : Segment) :
                                                          segmentGoal geom ea ia s = some (Controller.ia, ia) (personSpec geom ia).contains s = true

                                                          A segment finds the IA token iff the IA bears it — cycle-I Agree.

                                                          theorem Minimalist.CyclicAgree.eaAgrees_iff_exists (geom : Geometry) (probe : Probe.Articulation) (ea ia : Person) :
                                                          eaAgrees geom probe ea ia = true sprobe, (personSpec geom ia).contains s = false (personSpec geom ea).contains s = true

                                                          Existential characterization of the residue-based eaAgrees.

                                                          theorem Minimalist.CyclicAgree.eaIsLicensed_iff_segment_licensed (geom : Geometry) (probe : Probe.Articulation) (ea ia : Person) :
                                                          eaIsLicensed geom probe ea ia = true sprobe, (segProbe geom s).Licensed (goalTokens ea ia) (Controller.ea, ea)

                                                          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.

                                                          theorem Minimalist.CyclicAgree.plc_violation_iff_no_segment_licensed (geom : Geometry) (probe : Probe.Articulation) (ea ia : Person) :
                                                          isInverseContext geom probe ea ia = true sprobe, ¬(segProbe geom s).Licensed (goalTokens ea ia) (Controller.ea, ea)

                                                          PLC violation ↔ no segment's search licenses the EA token — the inverse-context characterization restated through the search substrate.

                                                          theorem Minimalist.CyclicAgree.cycleSegments_eq_segmentGoal_filters (geom : Geometry) (probe : Probe.Articulation) (ea ia : Person) :
                                                          cycleSegments geom probe ea ia = (List.filter (fun (s : Segment) => segmentGoal geom ea ia s == some (Controller.ia, ia)) probe, List.filter (fun (s : Segment) => segmentGoal geom ea ia s == some (Controller.ea, ea)) probe)

                                                          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)
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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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                                                                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→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: 3→1 is inverse despite residue, because EA (3P) can't match [addressee].

                                                                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).

                                                                Nishnaabemwin: 2→1 has a second-cycle effect (IA checks [π,participant], EA checks [addressee] on cycle II).

                                                                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.

                                                                theorem Minimalist.CyclicAgree.direct_inverse_exhaustive (geom : Geometry) (probe : Probe.Articulation) (ea ia : Person) :
                                                                (isDirectContext geom probe ea ia = true) (isInverseContext geom probe ea ia = true)

                                                                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.