Physical Symbol System Hypothesis Gagan Deep Kaur Roll No. 07408802 Course Seminar - CS 344.
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Transcript of Physical Symbol System Hypothesis Gagan Deep Kaur Roll No. 07408802 Course Seminar - CS 344.
Physical Symbol System
A PSS consists of
- Symbols - set of entities that are physical patterns - Symbol Structures - number of instances/tokens related in
some physical way- Processes – operate on these expressions to produce other
expressions
S6 S5 S4 S3S2 S1
Collection of “Expressions”
S12 S11
S10 S9S8 S7
S18S17S16S15S14S13
S24S23S22S21S20S19
S30S29S28S27S26S25
At any given time, a PSS contains- collection of expressions- processes to operate on these expressions creation, modification, reproduction, destruction
Physical Symbol System
Key Concepts
Designation – the symbol/expressions can refer to something else.
Interpretation – the expressions can refer to its own computational processes which the system can evoke and execute
Examples of Symbol Systems
System Symbol Expressions Processes
Logic And, Or, Not, Propositions (T/F) Rules of Inference
Algebra +, -, *, /, y, z, 1, 2, 3….
Equations(2+3=5)
Rules of Algebra
Digital Computer 0, 1 00000111000….. Program
-----Chess Chess Pieces Position of pieces on the board
Legal Chess Moves
Physical Symbol System Hypothesis
- By Allen Newell and Herbert Simon
“A physical symbol system has the necessary
and sufficient means for general intelligent action”
Claims
- Human thinking is a kind of symbol manipulation
- Symbol manipulation necessary for intelligence
- Machines can be intelligent, because
- Symbol manipulation is sufficient for intelligence
Core assumption of Strong AI
Grounds of PSS
Brain similar with a physical symbol system
Psychological Experiments – decision making, learning processes
Running AI programs –chess, checkers, theorem proving,
Clark – Productivity of Human Thoughts
Examples of PSS
System Symbol Expressions Processes
Digital Computer 0, 1 00000111000….. Program
-----Chess Chess Pieces Position of pieces on the board
Legal Chess Moves
Brain Encoded in brain Thoughts Mental Operations like thinking
AI Program Data Data Data
Merits
Computationally possible to encode symbolic human knowledge
Opened avenue for machine intelligence!
Implications
Appropriately programmed computer is capable of conscious thought
Machines can be made to think and have genuine understanding
Can Physical Symbol Systems Think?
Critiques
Serial manipulation of ≠ parallel and distributeddiscrete symbols processing (PSS) (Human Brain)
Dreyfus – Role of unconscious instincts than conscious symbol manipulation
Searle’s Chinese Room
Intelligence requires Understanding.
Does the program understands the symbols that it uses?
Does “symbols” have any meaning for the machine?
Conclusion
The question thus boiled down to this:
Could a system think or understand just by having right sort of program?
Is syntax enough to ensure “semantics” which is necessary for understanding.
References
Clark, Andy, “Philosophical Implications”, Artificial Intelligence, Ed. Margaret Boden, Academic Press, California, 1996
Dreyfus, Hubert, What Computers Can’t Do: The Limits of AI, Harper & Row, New York, 1979
Newell, Allen and Simon, Herbert, “Computer Science and Empirical Inquiry: Search and Symbols”, Mind Design II, Ed. John Hagueland, MIT Press, 1997,
Searle, John, “Minds, Brains and Programs”, Minds I, Ed. Douglas Hofstadter, and Daniel Dennett, Basic Books, 2001, P. 282-306
Wikipedia, Stanford EncyclopediaVarious Internet Sources For The Pictures!