Goteborg University Dialogue Systems Lab Comments on ”A Framework for Dialogue Act Specification” 4th Workshop on Multimodal Semantic Representation January Staffan Larsson Dept. of linguistics Göteborg University

Goteborg University Dialogue Systems Lab What the framework contains (among other things) Informal definitions of some central concepts –Dialogue act –Dialogue act type –Content –(Content type) –Communicative function –Meaning General formal definition of DA assignment system and taxonomy List of possible uses, and related constraints and requirements on DA taxonomies (???) The framework is intended as the basis for a repository (registry) of DA taxonomies –Presumably, since we cannot expect a consensus DA taxonomy anytime soon

Goteborg University Dialogue Systems Lab Definition of dialogue act A dialogue act is a unit in the semantic description of communicative behaviour produced by a sender and directed at an addressee specifying how the behaviour is intended to influence the context through understanding of the behaviour

Goteborg University Dialogue Systems Lab Definition of dialogue act A dialogue act is a unit in the semantic description of communicative behaviour in dialogues specifying how the behaviour is intended to change the information state of the addressee through his interpretation of the behaviour

Goteborg University Dialogue Systems Lab Two roads for a framework Avoid taking a stance on (be neutral w.r.t.) any controversial issues in the intended community of researchers –however, may result in a very weak (empty) framework –just because one person has an idiosyncratic (and perhaps incomprehensible) view on an issue, it is not necessarily “controversial” (understanding has limits...) Take a stand on (some) controversial issues –requires careful motivation –may still make framework less useful

Goteborg University Dialogue Systems Lab Which are the controversial questions? Traum (1999) lists 20 questions on dialogue act taxonomies divided into 4 groups –Defining dialogue acts –Dialogue act components –Relationships and complex acts –Taxonomic considerations On most of these issues, FDAS (Framework for DA Specification) is neutral On some issues, FDAS appears to take a stance which may not be shared by all researchers –increases the ”substance” of the framework –but may deter some potential users

Goteborg University Dialogue Systems Lab Q3: Under what conditions may an action said to have occurred? Kinds of conditions / criteria (can be combined) –a. intention of performer –b. form of the behaviour –c. achieved result –d. context in which the behaviour occurs In unproblematic cases, different criteria co- occur But in problematic cases some criteria hold and some don’t

Goteborg University Dialogue Systems Lab Q4: What is the role of speaker intention? Is an act defined in terms of the intention itself, or the recognition of the intention?

Goteborg University Dialogue Systems Lab Q5: What is the role of addressee uptake? Some researchers (Clark, Traum,...) require a grounding process before considering some dialogue acts (e.g. inform) successfully performed Meaning may also be negotiated Addressee may misinterpret and speaker may let it pass –A: The train leaves at five past five –B: OK, at five –A: So be there on time In addition to understanding an utterance, the addressee can accept or reject it

Goteborg University Dialogue Systems Lab Q13: Are there multi-agent dialogue acts? Some regard performance of illocutionary acts as collective action, in virtue of the grounding process DPs (Dialogue Participants) may e.g. complete each other’s utterances

Goteborg University Dialogue Systems Lab Definition of dialogue act again A dialogue act is a unit in the semantic description of communicative behaviour produced by a sender and directed at an addressee specifying how the behaviour is intended to influence the context through understanding of the behaviour

Goteborg University Dialogue Systems Lab but... Why is an act defined by the speaker’s intention, rather than e.g. the actual result? Is understanding enough? –contact, perception, uptake/acceptance Why just one sender, one addressee? –A single act may be produced by several DPs –and directed at several DPs (Why semantic? Why not pragmatic?)

Goteborg University Dialogue Systems Lab An alternative definition (example) A dialogue act is a unit in the semantic/pragmatic description of communicative behaviour produced by one or several sender(s) and directed at one or several addressee(s) specifying how the behaviour influences the context through uptake (understanding and acceptance) of the behaviour Perhaps one can come up with a definition which generalises over both this one and the previous

Goteborg University Dialogue Systems Lab Use of definition What is the status of the DA definition? Will it be enforced by the framework? How? Is it just a recommendation? Perhaps each DA taxonomy should make clear what position it takes on various controversial issues –e.g. by filling in a form

Goteborg University Dialogue Systems Lab Misc. comments

Goteborg University Dialogue Systems Lab Related concepts How does the concept of dialogue act relate to speech acts, communicative acts, dialogue moves? –To answer these questions, fairly detailed comparisons are needed

Goteborg University Dialogue Systems Lab DA type and IS update A DA type is distinguished by –(intended) context-changing effect (IS update) –observable features of behaviour Definition of DA type depends on IS type What counts as one IS update depends on –the type of IS e.g., can the IS capture the difference between a request for information and a question? –properties of the domain does it make any difference in the domain whether an utterance is a request or a question? –the capabilities of DPs e.g., can they distinguish normal and rhetorical questions? Criteria for distinguishing IS updates in a dialogue system vs. criteria for inter-annotator reliability in DA annotation

Goteborg University Dialogue Systems Lab DA types (= dimensions?) dialogue acts (Bunt) –task-driven –dialogue control feedback interaction management social obligations management –social obligations control dialogue acts (Allwood) –main message –communication management own communication management interactive communications management –feedback –turntaking –sequencing

Goteborg University Dialogue Systems Lab DA type – communicative function How are the concepts of ”dialogue act type” and ”communicative function” related? (bottom p.4) Dialogue act type = “dimension” (independent set of functions)? Utterance: ”Are you happy?” directed to “usr” –content: ?happy(usr) –function: ask –dialogue act: ask(?happy(usr)) –update: push ?happy(usr) on QUD (or similar) –dialogue act type: task-driven

Goteborg University Dialogue Systems Lab Function Each dimension (DA type) has a number of functions (which may or may not be mutually exclusive) Communicative functions (presumably this is an example?) –Information transfer question –check inform –answer »confirm –Action Discussion Function Does only the DA type “task driven” have comm. functions? –is “positive understanding feedback” a communicative function?

Goteborg University Dialogue Systems Lab Content and function ”it seems obvious that an utterance’s semantic content should not be used to determine its communicative function” (p.4) But... –”Can you close the window?” -> request –”Can you recite the phone book?” -> question –depends crucially on the action asked about, i.e. the content (and its relation to the context including commonsense knowledge) In 4.3 (Indirect speech acts) it is pointed out that figuring out indirect speech acts requires content Also in 4.5 for acts which require context

Goteborg University Dialogue Systems Lab Content type “Abstract content” Enough to determine e.g. whether the content is an action that the addressee has decision rights for, or not Example –A1: “We’re tired of you always hanging around.” –A2.1: “So you’re going home for Christmas” –A2.2: “So you’re leaving our home.”

Goteborg University Dialogue Systems Lab Information sources for DA assignment (p.5) Should perhaps include –4. semantic content + context information In GoDiS (Larsson 2002) dialogue moves are inferred from the relation between content and domain Examples: –”Give me information about flights to Paris!” –”Do you have flights to Paris?” –”I would like some information about flights to Paris.” –”Flights to Paris” All these are interpreted as the same set of moves: –{ answer(means-of-transport(flight)), answer(dest-city(paris))} –Simply because all utterances provide information relevant to certain issues in the domain Disregards intentions! –May not work generally, but for simple dialogue systems it works well

Goteborg University Dialogue Systems Lab Misc notes on Sec. 5 Increase uniformity of constraints and requirements w.r.t. uses of DA taxonomy –e.g. can annotation use contextual information? In subsection on dialogue management, focus on interpretation – but selection and generation is equally important

Goteborg University Dialogue Systems Lab Ranks and macros (related to section 5.1) Traum’s Q14: Can DAs be ”composed” of more primitive acts? –”ranks” (Halliday 1961) –Could there be some grammar or recipe for performance of an act of one stratum using acts of a lower stratum, similar to grammatical intra-sentence structure? Perhaps this could be included in the formal definitions –does not appear to be excluded by current formulation Related point: framework should allow for macros –single tag for combination of DAs on different levels

Goteborg University Dialogue Systems Lab Inter-annotator reliability Would be useful if framework supported computation of reliability Complex problem for multidimensional DA taxonomies

Goteborg University Dialogue Systems Lab Relational DAs For ”answer” or ”feedback” acts, should the framework support relating the DA to its antecedent? (cf. discourse relations)