Agreement Controller — Grammatical Role of the Controlling NP

@cite{corbett-2006} ch 2 §2.1, ch 6 §6.6

While Core/Agreement/Target.lean enumerates WHERE agreement morphology surfaces (Corbett 1991 Agreement Hierarchy), this file enumerates WHICH GRAMMATICAL ROLE the controlling NP plays. The two axes are orthogonal: a language can have subject-controlled verb agreement (Controller.subj × AgreementTarget.verb) and possessor-controlled attributive agreement (Controller.poss × AgreementTarget.attributive).

Typological labels

The labels here are typological metalanguage — Comrie/Dixon S/A/P

• grammatical-relation labels used across frameworks. Different theories operationalize them differently (LFG SUBJ ≠ Minimalist external argument ≠ RG 1), but at the level of CROSS-LINGUISTIC DESCRIPTION (which is what Core.Morphology.MorphCategory.agreement records), the labels are reasonably consensual. Framework-specific projections (LFG analysis → Controller, Minimalist analysis → Controller) live in Theories/Syntax/.

Cases derived from Corbett 2006

@cite{corbett-2006} §2.1 surveys controller TYPES (canonical NPs, defective clauses §2.1.2, weather-verb absent controllers §2.1.3, possessive adjectives §2.1.4, qualitative adjectives §2.1.5). Within canonical NP controllers, the orthogonal GRAMMATICAL-ROLE dimension is treated in §6.6 — Hindi/Urdu (p. 195): "if the subject is in the nominative, the verb agrees with it; otherwise, if the object is in the nominative, the verb agrees with that; otherwise the verb shows default agreement". This 3-way subj/obj/default rule is the canonical Indo-Aryan pattern; other languages fold in indirect objects (recipients), possessors (Upper Sorbian §2.1.4), and rarely obliques.

Anderson 2006 Ch 5 §5.2 motivation

The substrate gap that prompted this enum: Anderson's split/doubled AVC typology turns on "subjects on both AUX and LV; objects only on LV" — a generalization unstateable when MorphCategory.agreement collapses subj/obj. Parameterizing agreement on Controller makes the Anderson Ch 5 typology directly Lean-checkable: dist.onLex.contains (.agreement .obj) ∧ ¬ dist.onAux.contains (.agreement .obj).

Bybee 1985 motivation

Phenomena/Morphology/Studies/Bybee1985.lean:255-257 already encodes Bybee's source distinction personAgr / personAgrObj / genderAgr but collapses all three onto flat .agreement in the substrate projection. With the parametric form, the projection round-trips: personAgr → .agreement .subj, personAgrObj → .agreement .obj.

What's NOT here

• Case — case-marking (nom/erg/abs/dat/...) is orthogonal to grammatical role. Quirky-case subjects in Icelandic, ergative-case agents in Tsakhur, etc. are case phenomena, not controller-role phenomena. Case lives in Core/Case/.
• φ-features (person, number, gender) — these are properties of the CONTROLLER NP that determine agreement values. Not encoded in the controller-role enum itself.
• Animacy / topicality / focus — agreement conditions per @cite{corbett-2006} ch 6, not controller-role labels.

inductive Core.Agreement.Controller : Type

Grammatical role of the agreement controller. Cross-linguistically motivated typological labels per @cite{corbett-2006} §6.6.

• subj : Controller

  Subject (S in intransitive, A in transitive). The unmarked case cross-linguistically. Russian kniga controlling verb agreement; English he controlling -s.

• obj : Controller

  Direct object (P in transitive). In ergative-absolutive systems, the absolutive argument; cf. Dargwa gender-prefix agreement controlled by absolutive (@cite{corbett-2006} §6.5 ex. 21-26).

• iobj : Controller

  Indirect object / recipient (G in ditransitive). Some Bantu and Romance dialects show recipient agreement on the verb.

• poss : Controller

  Possessor. Hungarian possessive suffix; Upper Sorbian moj-eho muž-ow-a sotr-a where the possessive adjective controls the attributive (@cite{corbett-2006} §2.1.4).

• obl : Controller

  Oblique (rare; some Bantu locative agreement). Provided for typological completeness.

• defaultAgr : Controller

  No canonical controller. Weather verbs (Italian piove @cite{corbett-2006} §2.1.3), defective clausal/infinitival controllers (§2.1.2): the target shows default agreement (typically 3sg.M in IE languages).

@[implicit_reducible]

instance Core.Agreement.instDecidableEqController : DecidableEq Controller

Equations

• Core.Agreement.instDecidableEqController x✝ y✝ = if h : x✝.ctorIdx = y✝.ctorIdx then isTrue ⋯ else isFalse ⋯

def Core.Agreement.instReprController.repr : Controller → Nat → Std.Format

Equations

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

@[implicit_reducible]

instance Core.Agreement.instReprController : Repr Controller

Equations

• Core.Agreement.instReprController = { reprPrec := Core.Agreement.instReprController.repr }

def Core.Agreement.instInhabitedController.default : Controller

Equations

• Core.Agreement.instInhabitedController.default = Core.Agreement.Controller.subj

@[implicit_reducible]

instance Core.Agreement.instInhabitedController : Inhabited Controller

Equations

• Core.Agreement.instInhabitedController = { default := Core.Agreement.instInhabitedController.default }