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Tadahiro Taniguchi, Associate professorCollege of information tech.&sci., Ritsumeikan univ.
Shonanvillage
Shonan meeting2013/11/11 ‐ 14
Tadahiro Taniguchi @tanichu Associate professor, Emergent system laboratory College of information science and technology,
Ritsumeikan University, Japan 2006, PhD Eng. , Kyoto university 2008‐ Assistant professor 2010‐ Associate professor
Machine learning
Cognitive robotics
Decentralized autonomous system
Human communication
Symbol Emergence in Robotics
Computational understandings of mental development‐ From behavioral learning to language acquisition ‐
A human child acquires many physical skills, concepts and knowledge including language through physical and social interaction with his/her environment.
How can we become able to communicate using symbolic system?
We’d like to obtain computationalunder standings of mental development and symbol emergence.
3
Constructive approach towards human intelligenceenabling semiotic communication
Symbol grounding problem How can a robot “ground” his/her symbol to the real physical world? [Harnad ‘90] The robot has to give some meaning to a symbol in its symbolic system designed by a human designer through sensor‐motor interaction with its environment.
Arbitrary nature of symbol (in semiotics) Arbitrariness of labeling/naming Arbitrariness of categorization/segmentation
SGP implicitly assumes that human “arbitrarily evolved” symbolic system is a “true” symbolic system.
Should a symbolic system for a robot be same as human’s ?
SGP ismissing
Understanding that symbolic system is an emergent property of human cognitive and social system “Worlds of robots”
“Worlds of animals” (Uexküll 1934) Umwelt (self‐centered world) Animals can receive information only from
their sensor‐motor system. A human has to obtain various behaviors, concepts
and language on the basis of experiences in his/her umwelt (closed cognitive system).
Human Symbolic system should be understand on the basis of human embodiment (sensor‐motor system).
Concepts have to be formedon the basis of sensor‐motor information
in a bottom‐up way
Ernst Mach’s famous picture
"Early Scheme for a circular Feedback Circle by Uxkull
Sharedsymbolic system
Social constraints in semiotic communication
Concept formation is not “enough” for semiotic communication.
We have to share a symbolic system involving syntax, semantics and pragmatics lexicon and mutual belief
Sheep the coming,aren’t they!!!
(true) A thief is coming!!
bad naming
bad syntax
bad interpretation
It’s impossible to help her
Sharedsymbolic system
Social constraints in semiotic communication
Concept formation is not “enough” for semiotic communication.
We have to share a symbolic system involving syntax, semantics and lexicon pragmatics and mutual belief
A thief is coming!!
!
constraintconstraint
constraint
constraint
speech generation
situation recognitioninterpretation
decision making(;O;)
Emergent System Emergent property
Through local interaction between elements of a system, global (or macro‐level) order or pattern emerges. The macro‐level order becomes constraints of micro‐level dynamics, and governs the micro‐level interaction. Such bidirectional process makes the system have novel function, morphology and/or behavior.
constraintemergencemicro‐macro loop
Before introducing “symbol emergent system”, please remind....
Symbol emergent system
Shared lexicon, syntax,pragmatics, semantics,and mutual belief
Concept formation throughinteraction with environment
Semiotic / Social interaction
Physical interaction
Symbolic SystemEmergence
谷口忠大. 「コミュニケーションするロボットは創れるか‐記号創発システムへの構成論的アプローチ」(2010).Tadahiro Taniguchi “Constructive approach toward symbol emergence system” (in Japanese)
Symbol emergence in robotics (SER) Constructive approach toward symbol emergent systems “Constructive” viewpoint to an intelligent system which uses symbolic system.
1. Constructive approach Understanding human intelligence by constructing robots obtaining symbolic system
2. Constructivism Understanding human intelligence which construct his/her subjective world (Umwelt).
(c) Nagai lab.
Understandingby developing “models”
Topics in SER
multimodalcommunication
conceptformation
language acquisitionand mental development
learning motor skillsand segmentation of
time‐series infomation
emergence of communication
learning interaction strategy
Prof. Nagai
Segmentation of sensor‐motortime‐series information Dynamics in sensor‐motor time‐
series information changes depending on its environmental situations.
An autonomous system should differentiate such situations and obtain representations.
How do humans and how can the robots segment the time‐series data?
What is the criteria of segmentation?What is an adequate computational algorithm for the segmentation?
Modular learning architecturefor segmenting sensor‐motor time series MOSAIC [Kawato et al.]
Mixture of experts [Jacobs et al.] HAMMER [Yiannis et al.]
Dual schemata model [Taniguchi et al.]
http://www.cns.atr.jp/cnb/HarunoG/harunoG.ja.html
How can we grasp long‐term context?
“Segment” corresponds toa linear systemlocal informationa short‐term event
T. Taniguchi, T. Sawaragi, "Incremental acquisition of multiple nonlinear forward models based on differentiation process of schema model“, Neural Networks, Vol.21 (1), pp.13‐27 .(2008)
階層的な分節構造の自己組織的な獲得
Representation of a room and a part of a room and was encoded in RNNin a hierarchical manner.
Hierarchical mixture ofRNN experts [Tani and Norfi 1999]
Dynamical System ApproachDynamical System Approach Symbols are implicitly obtained. It is difficult to understand how the system formed concepts.
Double articulation structure insemiotic data Semiotic time‐series data often has double articulation
Speech signal is a continuous and high‐dimensional time‐series. Spoken sentence is considered as a sequence of phoneme People don’t give a meaning to a phoneme, but give a meaning to a wordwhich is a sequence of phoneme.
h a u m ʌ́ tʃ I z ð í s
[h a u ] [m ʌ́ tʃ] [ i z ] [ð í s]
How much is this?semantic
(meaningful)
meaningless
unsegmented
Double Articulation Analyzerto estimate latent double articulation structure
Unsupervised learning Estimating
Language model Emission distribution Segments and chunks
Conditions Unknown number of
words and letters Unknown emission
distributions Inference
Approximate Inference Procedure of Double Articulation Analyzer [Taniguchi ‘11]
Nonparametric Bayesian approach
iHMM[Fox ‘07]
NPYLM[Moachihashi ‘09]
Tadahiro Taniguchi, Shogo Nagasaka, Double Articulation Analyzer for Unsegmented Human Motion using Pitman‐Yor Language model and Infinite Hidden Markov Model, 2011 IEEE/SICE SII.(2011)
sticky HDP‐HMM [Fox ‘07]
An infinite HMM is an HMM which can estimate the number of hidden state flexibly (potentially infinite)[Beal ‘02] [Teh ‘06]
Sticky HDP‐HMM is a generative model for iHMMwith a stickiness parameter [Fox ‘07].
Fox et al. developed fast inference algorithm with weak‐limit approximation.
Gaussian emission distribution
β
z1
γ
λ θk∞
πkα
y1
z2
y2
z3
y3
zT
yT
κ
iHMM[Fox ‘07]
E.B. Fox, E.B. Sudderth, M.I. Jordan, A.S. Willsky, "A Sticky HDP‐HMM with Application to Speaker Diarization," Annals of Applied Statistics, June 2011. (First appeared asMIT LIDS Technical Report P‐2777, November 2007.)
Unsupervised morphological analysis Morphological analysis
To segment sentences into words(morpheme).
This usually requires dictionary(preexisting knowledge of language model).
Unsupervised morphological analysis It does not assume preexisting dictionary.
Mochihashi proposed an unsupervised morphological analysis method based on Nested Pitman‐Yor language model (NPYLM)[Mochihashi ‘09].
Thisisanapple ‐> This is an appleわたしはたなかです. ‐> わたし は たなか です
http://chasen.org/~daiti‐m/paper/nl190segment‐slides.pdf
NPYLM[Moachihashi ‘09]
NPYLM [Mochihashi ‘09]
(Nested Pitman‐Yor Language Model) Mochihashi developed NPYLM for unsupervised morphological analysis.
NPYLM has word n‐gram model and letter ngram model, hierarchically. Each adopts hierarchical Pitman‐Yor language model as a language model (smoothing method).
Bayesian nonparametric model Efficient blocked Gibbs sampler
Daichi Mochihashi, Takeshi Yamada, Naonori Ueda."Bayesian Unsupervised Word Segmentation with Nested Pitman‐Yor Language Modeling". ACL‐IJCNLP 2009, pp.100‐108, 2009.
Application of Double Articulation Analyzer
DAA
Human motion data
Driving behavior
• Imitation learning [Taniguchi ‘11]• Motion segmentation [Taniguchi’11]
• Extracting driving chunk [Nagasaka ‘12]• Detecting intentional changing points [Takenaka ‘12]• Prediction [Taniguchi ‘12]• Video summarization [Takenaka ‘12]• For topic modeling []
Auditory data*
collaborative workwith DENSO co.
collaborative workwith Nagai lab.
• Language acquisition [Araki ‘12] bottle !!
*Only NPYLM was used.
Contextual Scene Segmentation of Driving Behavior based on Double Articulation Analyzer [Takenaka ‘12] DAA could extract changing points of driving context recognized by human
Kazuhito Takenaka, Takashi Bando, Shogo Nagasaka, Tadahiro Taniguchi, Kentarou Hitomi, Contextual Scene Segmentation of Driving Behavior based on Double Articulation Analyzer, IEEE/RSJ International Conference on Intelligent Robots and Systems 2012 (IROS 2012), 4847‐4852 .(2012)
Semiotic Prediction of Driving Behavior using Unsupervised Double Articulation Analyzer [Taniguchi ‘12]
Tadahiro Taniguchi, Shogo Nagasaka, Kentarou Hitomi, Naiwala P. Chandrasiri, and Takashi BandoSemiotic Prediction of Driving Behavior using Unsupervised Double Articulation Analyzer2012 IEEE Intelligent Vehicles Symposium, 849 ‐ 854 .(2012)
Averaged number of correctlypredicted hidden states
Histogram
Drive Video Summarization based on Double Articulation Structure of Driving Behavior [Takenaka ‘12]
Kazuhito Takenaka, Takashi Bando, Shogo Nagasaka, Tadahiro Taniguchi, "Drive Video Summarization based on Double Articulation Structure of Driving Behavior", ACM multim media 2012,
http://www.youtube.com/watch?v=knwiO6dVbnY
Online Learning of Concepts and Words Using Multimodal LDA and Hierarchical Pitman‐Yor Language Model [Araki ‘12] Connecting multimodal categorization and word segmentation to achieve language acquisition through daily interaction.
Takaya Araki, Tomoaki Nakamura, Takayuki Nagai, Shogo Nagasaka, Tadahiro Taniguchi, Naoto IwahashiOnline Learning of Concepts and Words Using Multimodal LDA and Hierarchical Pitman‐Yor Language ModelIEEE/RSJ International Conference on Intelligent Robots and Systems 2012 (IROS 2012), 1623‐1630 .(2012)
Conclusion Summary
Defining the symbol emergence system Introducing symbol emergence in robotics Introducing double articulation analyzer
Current challenge Unsupervised lexicon acquisition using double articulation analyzer and multi‐modal categorization
Discussion topic What is the important feature of language which we have to model to obtain computational understanding of human language.