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This presentation is dedicated to the memory of This presentation is dedicated to the memory of journalist Danny Pearl, murdered in Pakistan journalist Danny Pearl, murdered in Pakistan
in February 2002, and to the pioneering in February 2002, and to the pioneering research of his father Judea Pearl. Danny research of his father Judea Pearl. Danny
Pearl’s spirit will live on in the work of those Pearl’s spirit will live on in the work of those who apply his father’s work to protect the open who apply his father’s work to protect the open
society for which he gave his life.society for which he gave his life.
The Daniel Pearl Foundation (http://www.danielpearl.org) was formed in memory of journalist Daniel Pearl to further the ideals that inspired Daniel's life and work.
Real world with real Real world with real representationrepresentationcreated by real conscious created by real conscious subsystemsubsystem
Artificial world with Artificial world with simulated representationsimulated representationcreated by simulated created by simulated conscious subsystemconscious subsystem
The Fusion Challenge• Fusion is the process of incorporating information from
different sources into a single “fused” representation• Why fusion is difficult:
– Vast quantities of sensor information– Real-time processing requirements– Restrictions on weight, communication bandwidth– Need to integrate physical and geometrical models with
qualitative knowledge– Noisy, unreliable, ambiguous data– Active attempts at deception– Requirement for robustness to new or little-known entities
• Why fusion is important:– Features that are meaningless in isolation are definitive in
Paradigm Shift in Computing• Old paradigm: Algorithms running on Turing machines
– Deterministic steps transform inputs into outputs– Result is either right or wrong– Semantics based on Boolean logic
• New paradigm: Economy of SW agents running on physical symbol system– Agents make decisions (deterministic or stochastic) to achieve objectives– “Program” replaced by dynamic system improving solution quality over time– Semantics based on decision theory / game theory / stochastic processes
• Hardware realizations of physical symbol systems– Physical systems minimize action– Decision theoretic systems maximize utility / minimize loss– Hardware realization of physical symbol system maps action to utility– Programming languages are replaced by specification / interaction languages– Software designer specifies goals, rewards and information flows– Unified theory spans sub-symbolic to cognitive levels
– Constants (stand for particular named objects)– Variables (stand for generic unnamed objects)– Functions (allow objects to be referred to indirectly)
» Location(x)» MotherOf(y)
– Predicates (represent hypotheses that can be true or false)» Guilty(s)» Near(John,GroceryStore32)
• Syntax:– Atomic sentences– Composition rules for forming compound sentences from atomic sentences
• Semantics– Tarski invented the standard semantics for first-order logic– Compositional: meaning of sentence depends on meaning of parts– Valid sentence is true in all interpretations of a language; unsatisfiable sentence cannot be
• FOL “has enough expressive power to define all of mathematics, every digital computer that has ever been built, and the semantics of every version of logic, including itself.” (Sowa,2000)
• Issues:– Cannot express generalizations about sets, predicates, functions– Cannot represent gradations of plausibility– No built-in approaches to
» Categories» Time and space» Causality» Action» Events» Value
• Represent knowledge as collection of partial Bayesian networks– Instantiate & compose into problem-specific models– MEBN is to BN as algebra is to arithmetic
• Consistency constraints ensure existence of global probability distribution
• Integrates classical first-order logic with probability– Predicates Boolean random variables– Functions Non-Boolean random variables– Existence results
» MTheory implicitly represents coherent joint distribution on interpretations of associated first-order theory
» Universal MTheory specifies joint distribution on satisfiable first-order sentences & conditional distribution given any consistent finite set of axioms
• Provides logical basis for probabilistic databases (Probabilistic Relational Models research @ Stanford)