Module drs 

Discourse Representation Structure (DRS) for anaphora resolution and scope tracking.

This module implements a simplified DRS following the theory developed by Hans Kamp and Uwe Reyle. The DRS tracks referents (discourse entities) across sentences and handles pronoun resolution, donkey anaphora, and quantifier scope.

Core Concepts

• Box: A scope container holding referents and conditions. Boxes nest to form scope islands (conditionals, quantifiers, negation).
• Referent: A discourse entity with a variable, noun class, gender, and number. Introduced by indefinites, proper names, or quantifiers.
• Accessibility: Whether a referent can be accessed from a given scope. Negation and disjunction block accessibility outward.

Key Types

Type	Purpose
Drs	The box hierarchy tracking referents and their scopes
WorldState	Unified discourse state persisting across sentences
BoxType	Classification of scope containers (Main, Negation, Modal, etc.)
Referent	A discourse entity with gender, number, and source information
ScopeError	Error when pronoun resolution fails due to scope constraints

Accessibility Rules

A pronoun in box B can access referent R in box A if:

1. A is B (same box)
2. A is an ancestor of B (parent chain)
3. A is a conditional antecedent and B is the consequent of the same conditional
4. A is a universal restrictor and B is the universal scope

Referents in negation or disjunction boxes are NEVER accessible from outside.

Example

“If a farmer owns a donkey, he beats it.”

• “a farmer” introduces referent x in conditional antecedent box
• “a donkey” introduces referent y in conditional antecedent box
• “he” resolves to x (accessible from consequent)
• “it” resolves to y (accessible from consequent)
• Both receive universal quantification due to conditional DRS signature

Structs

Drs

DrsBox

ModalContext

Modal context for tracking hypothetical worlds across sentences. Enables modal subordination: “A wolf might walk in. It would eat you.”

Referent

TelescopeCandidate

A referent that may be accessed via telescoping across sentence boundaries

TimeConstraint

WorldState

The unified discourse state that persists across sentences.

Enums

BoxType

Case

Grammatical case (for pronouns).

Gender

Grammatical gender (for pronouns and agreement).

Number

Grammatical number for nouns and agreement.

OwnershipState

ReferentSource

ScopeError

Error when pronoun resolution fails due to scope constraints

ScopePath

Path segment for navigating to insertion point during AST restructuring

TimeRelation