vector symbolic architectures: constructions in the brain simon d. levy washington lee university...

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Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington & Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage Value Solutions / LaTrobe University Melbourne, Australia

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Page 1: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Vector Symbolic Architectures: Constructions in the Brain

Simon D. LevyWashington & Lee University

Lexington, Virginia, USA

Ross GaylerBaycorp Advantage Value Solutions /

LaTrobe UniversityMelbourne, Australia

Page 2: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

The Appeal of Connectionism(Rumelhart &

McClelland 1986)

Page 3: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

WALK

WALKED

Page 4: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

ROAR

ROARED

Page 5: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

SPEAK

SPOKE

Page 6: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

GO

WENT

Page 7: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

ignores(mary, john)

Mary won’t give John the time of day.

Page 8: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Language Isn’t (Just)

Association: Jackendoff’s

Four Challenges for

Cognitive Neuroscience

Page 9: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Challenge I: The Binding Problem

+

? ? ? ?

Page 10: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Solution? Local Representations

Page 11: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Local Representations

Page 12: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Challenge II: The Problem of Two

?

Page 13: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Challenge III: The Problem of Variables

Challenge IV: Working Memory vs. Long-Term Memory

ignores(X, Y)

X won’t give Y the time of day.

Page 14: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Vector Symbolic Architectures

(Plate 1991; Kanerva 1994; Gayler 1998)

Page 15: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Binding

Page 16: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Binding

Page 17: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Bundling

+ =

Page 18: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Unbinding (query)

Page 19: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Reduction

Page 20: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Composition / Recursion

Page 21: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Variables

X

john

Page 22: Vector Symbolic Architectures: Constructions in the Brain Simon D. Levy Washington  Lee University Lexington, Virginia, USA Ross Gayler Baycorp Advantage

Conclusions / Future Work

•VSAs address Jackendoff’s first three challenges

•Can be implemented as spiking neurons (Eliasmith 2004)

•Remaining challenge: constructions (long-term memory) to map from conceptual structure (working memory) to symbol sequences