Towards multimodal meaning representation Harry Bunt & Laurent Romary LREC Workshop on standards for language resources Las Palmas, May 2002

Scope What should we consider as meaning? –How the processing of the input should lead to some update of the information state of the system (domain model, discourse model, user model, etc.); –This comprises both propositional content and communicative function. Such a representation: –Should support both interpretation and generation; –Should support any kind of multimodal input and output; –Should support the variety of semantic theories;

Objectives –Provide interface formats within a MM dialogue architecture Incremental construction (reference interpretation etc.) up to a final representation (e.g. fixed frame à la MUC) or system action/feedback; Should also be a basis for the definition of annotation schemes of MM semantic content. –Specification and comparison of application-specific representations Towards a framework allowing one to compare existing representations (e.g. M3L) or define a new one, while ensuring some level of interoperability between these.

What it is not A domain model representation, or an ontology –There is OIL, DAML, Topic Maps, UNL etc. A representation of lower-level linguistic or gestural information (e.g. syntax, etc.) –Some features may be percolated, though, or pointed to… A representation of the underlying processes –Focus on the output of what is done by a given module

Basic constraints Expressive and semantic adequacy –Coverage of phenomena and inferencing capacities Uniformity (representation for various types of inputs and outputs) Incrementality (usable at various stages) –Before/after fusion, semantic/pragmatic aspects Underspecification and partiality Openness and Extensibility –Compatibility with various theories and approaches –Method for designing schemas (XML or others), rather than one specific schema

Methodology Basic components –Represent the general organization of any semantic structure –Parameterized by data categories taken from a common registry application specific data categories General mechanisms –To make the thing work General categories –Descriptive categories available to all formats

Basic components (1) Temporal structures (“events”) –Dialogue turns/utterance –Gestures –Actions on/in the task Referential structures (“participants”) –Individuals and objects participating in an event Comprises spatial structures –Propositional content

Basic components (2) Restrictions (on temporal and referential structures) –E.g. Gesture types, Linguistic modifiers, Dialogue acts, etc. Dependency structures (linking events and referential structures) –E.g. Participant roles (cf. AGENT-SOURCE- GOAL), Discourse/rhetorical structure, temporal relations

General mechanisms Links –Internal links –To lower levels (syntactic structures, prosodic cues, gestural trajectories, etc.) –To domain model (types and instances) Alternatives (cf. ambiguities) –E.g. disjunction of internal links

General categories Architectural –Producer (consumer?) of the information, confidence, devices Environmental –Time stamps, spatial information (speaker’s position, graphical configurations, gestural trajectories etc.) Interactional –Speaker (user state?), other addressees etc.

Combining basic components and data categories Just to illustrate things…

Example utterance present wanttogo … sing agent In black: basic components and mechanisms (meta-model of semantic representation) In blue: parameter component chosen from reference registries Categories Values Pointer to speaker’s characteristics Peter: I want to go …

utterance <dialAct cert=“0.8”>Order <dialAct cert=“0.3”>Inform present active none wanttogo … I Pronoun sing first … Paris ProperNoun third … Nancy ProperNoun third … agent source goal I want to go from Paris to Nancy

utterance Order present active none wanttogo … gestural : designation I … here adverb there adverb co-designation I want to go from here to there

Future work SIGSEM Working group on meaning representations (ACL) –Liaison with ISO TC37/SC4 - linguistic resources Preparation of a working draft –Liaison with Isle –Liaison with SIGMedia and SIGDial –W3C/VoiceXML