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Understanding Naturally Conveyed Explanations of Device Behavior. Michael Oltmans and Randall Davis MIT Artificial Intelligence Lab. Roadmap. The problem Our approach Implementation System architecture How ASSISTANCE interprets descriptions Demonstrating understanding
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Understanding Naturally Conveyed Explanations of Device Behavior Michael Oltmans and Randall Davis MIT Artificial Intelligence Lab
Roadmap • The problem • Our approach • Implementation • System architecture • How ASSISTANCE interprets descriptions • Demonstrating understanding • Evaluation and contributions • Related and future work
Sketches Models • We have a sketch of a device • A simulation model can be generated from the sketch • Life is good… or is it?
The Problem • No representation of intended behavior • People talk and sketch but the computer doesn’t understand
Task • Understand descriptions of device behavior: • Given: • A model of the device’s structure • A natural explanation of the behavior • Generate a causal model of behavior
Roadmap • The problem • Our approach • Implementation • System architecture • How ASSISTANCE interprets descriptions • Demonstrating understanding • Evaluation and contributions • Related and future work
Naturally Conveyed Explanations • Natural input modalities • Sketched devices • Sketched gestures • Speech • Natural content of descriptions • Causal • Behavioral
Sources of power • Conventions in explanations aide interpretation • Description order suggests causal order • Constrained vocabulary • Overlapping descriptions provide constraints on interpretations
Roadmap • The problem • Our approach • Implementation • System architecture • How ASSISTANCE interprets descriptions • Demonstrating understanding • Evaluation and contributions • Related and future work
Sketch Speech • ASSIST • Recognize sketch • ViaVoice™ • Recognize speech • Parse • ASSISTANCE • Interpret explanation • LTRE • Truth Maintenance • Rule System Causal Model and Simulation
Outputs • Consistent causal model • Tree • Nodes are events • Links indicate causal relationships • Demonstration of understanding • Natural language descriptions of causality • Parameter constraints
The Representation of Utterances • Input comes from ViaVoice™ : • Grammar constructed based on observed explanations • Tagged with parts of speech and semantic categories
Representing the parse tree “body 1 pushes body 2” SENTENCE SIMPLE_SENTENCE (… “body 1 pushes body 2” (S0) t1) SUBJECT NOUN NOUN-PHRASE (… “body 1” (S0 t1) t2) VERB_PHRASE (… “pushes body 2” (S0 t1) t3) PROPELS VERB (… “pushes” (S0 t1 t3) t4) DIRECT_OBJECT NOUN NOUN-PHRASE (… “body 2” (S0 t1 t3) t5)
Steps In Interpreting Explanations: • Infer motions from annotations and build event representations • Find causal connections • Search for consistent causal structures • Pick best causal structure
Step 1: Inferring Motions from Annotations • Inputs: • Arrows • Utterances • “moves,” “pushes,” “the spring releases” • Outputs: • (moves body-1 moves-body-1-394) • (describes arrow-2 moves-body-1-394)
Inferring Motion From Arrows • Rule triggers: • Arrow • Arrow referent (i.e. a body) • The body is mobile • Rule body records that: • The body moves • The arrow describes the path
Inferring Motion From Arrows (rule ((:TRUE (arrow ?arrow) :VAR ?f1) (:TRUE (arrow-referent ?arrow ?body) :VAR ?f2) (:TRUE (can-move ?body) :VAR ?f3) (:TRUE (name ?name ?body))) (rlet ((?id (new-id “Moves” ?name))) (rassert! (:implies (:AND ?f1 ?f2 ?f3) (:AND (moves ?body ?id) (describes ?arrow ?id))) :ARROW-IS-MOTION)))
Multi-Modal References • Match a sentence whose subject is “this” and a pointing gesture • Assert the referent as the subject of the sentence • Limitations: • User must point at referent before the utterance • Allow one “this” per utterance
Event 1 (moves body-1 id-1) (moves body-1 id-2) Redundant Events • Redundant explanations lead to multiple move statements for some events • Merge them into a unique event statement “Body 1” falls
Step 2: Find Causal Connections • Plausible causes • Arrow indicating motion near another object • Exogenous forces • Definite causes • “When … then …” utterances • “Body 1 pushes body 2”
Step 3: Search for Consistent Causal Structures • Some events have several possible causes • Find consistent causal chains • Search • Forward looking depth-first-search • Avoids repeating bad choices by recording bad combinations of assumptions
Step 4: Find the Best Interpretation • Filter out interpretations that have unnecessary exogenous causes • Pick the interpretation that most closely matches the explanation order • While there are multiple valid interpretations • Choose one event with multiple possible causes • Assume the causal relation whose cause has the earliest description time
Answer Queries and Adjust Parameters • Queries: • Designer: What is body 2 involved in? • ASSISTANCE: The motion of body 3 causes the motion of body 2 which causes the motion of body 5 • Parameter Adjustment • Set spring length
Roadmap • The problem • Our approach • Implementation • System architecture • How ASSISTANCE interprets descriptions • Demonstrating understanding • Evaluation and contributions • Related and future work
Limitations of the Implementation • Scope of applicability restricted • State transitions are one step deep • Cannot handle conjunctions of causes • Limited knowledge about common device patterns • Latches, linkages, etc… • Supports and prevents • Natural language limitations • Use a full featured NL system like START • Formally determine the grammar
Evaluation of the Approach • Advantages • Focus on behavior in accordance with survey results • Move away from rigidity of WIMP interfaces • Similar to person-to-person interaction • Alternatives • More dialog and feedback • Natural vs. efficient • Open claim that the domain is adequately constrained
Contributions • Understanding naturally conveyed descriptions of behavior • Generating representations of device behavior • Match the designer’s explanation • Generate simple explanations of causality • Allow the calculation of simulation parameters
Related Work • Understanding device sketches • Alvarado 2000 • Multimodal interfaces • Oviatt and Cohen • Causality • C. Rieger and M. Grinberg 1977
Future Work • Direct manipulation • Dialog • Expand natural language capabilities • Smart design tools