Further Cognitive Systems

1
Further Cognitive Systems

• Learning
• Environmental interaction
• Artificial cognition?
• Current cognitive systems
• Science-fiction v fact
• Architectures
• Perception, Representation, Reasoning, Learning
  Action
• Learning Cognitive Systems
• Problems in LCS
• Advances in LCS

2
Artificial Cognition

• How to build a mind?
• Base it on a computer
• Use a high level computer programme
• What is a computer?
• Are there any limitations to a computers
  ability?
• How does this affect our mind building?

3
Theory of Computation

• Disclaimer
• Theory of Computation part of Computer Science.
• Therefore, theoretical and mathematical
• Fields included
• Set Theory
• Graph Theory
• Logic
• Computerability Theory
• Complexity theory
• Whole courses and books available!
• (e.g. Introduction to the Theory of Computation,
  Michael Sipser, PWS publishing)

4
Finite State Automata

• Deterministic FA
• Every step of computation follows in a unique way
  from the preceding step
• 0 0
• 1
• 1
• Nondeterministic FA
• Generalisation of determinism, so every
  deterministic finite automaton is automatically a
  nondeterministic finite automaton
• 0,1 0,1
• 1 0, e

5
Formal Systems

• MIU
• Rules
• If you possess a string whose last letter is I,
  you can add on a U at the end.
• Suppose you have Mx, then you may add Mxx to your
  collection
• If III occurs in one of the strings in your
  collection, you may make a new string with U in
  place of III
• If UU occurs inside one of your strings, you can
  drop it
• Starting with MI can you get to MU?

6
Algorithms

• An algorithm is a collection of simple
  instructions for carrying out some task
• A modern definition states that the procedure to
  achieve a specified result is an algorithm iff
• Each step is blind (each step needs no further
  insight)
• Steps to follow on blindly (no insight needed
  to determine the next step)
• A result is guaranteed after a finite number of
  steps

7
Effective Methods

• A computer was originally a human assistant who
  calculated by rote in accordance with some
  effective method
• A method is effective iff
• It demands no insight or ingenuity from the
  human computer
• Produces a result in a finite number of steps
• Notion of an effective method is closely linked
  with that of an algorithm

8
Mathematical Systems

• A consistent system is one that contains no
  contradictions
• A complete system is one in which every
  mathematical statement is provable
• Decidable means that there is an effective method
  for telling of each mathematical statement,
  whether or not it is provable within the system
• Godels incompleteness theorem proved that it is
  not possible to express all systems in a
  complete, consistent and decidable formal system

9
Halting Problem

• The halting problem is a decision problem which
  can be informally stated as follows
• Given a description of an algorithm and its
  initial input, determine whether the algorithm,
  when executed on this input, ever halts (the
  alternative is that it runs forever without
  halting).
• Turing proved that a general algorithm to solve
  the halting problem for all possible inputs
  cannot exist.
• See
• http//en.wikipedia.org/wiki/Halting_problem

10
Turing Machine

• A Turing machine is an abstract representation of
  a computing device. It consists of a
• read/write head that scans a (possibly infinite)
• one-dimensional (bi-directional) tape divided
  into squares, each of which is inscribed with a 0
  or 1.
• Computation begins with the machine, in a given
  "state", scanning a square. It erases what it
  finds there, prints a 0 or 1, moves to an
  adjacent square, and goes into a new state. This
  behavior is completely determined by three
  parameters (1) the state the machine is in,
• (2) the number on the square it is scanning, and
  (3) a table of instructions.
• The table of instructions specifies, for each
  state and binary input, what the machine should
  write, which direction it should move in, and
  which state it should go into.
• E.g., "If in State 1 scanning a 0 print 1, move
  left, and go into State 3".
• The table can list only finitely many states,
  each of which becomes implicitly defined by the
  role it plays in the table of instructions. These
  states are often referred to as the "functional
  states" of the machine.

11
Variants of Turing Machines

• Universal Turing Machine, Turing showed that in
  principle the operation of any TM can be
  simulated by a UTM
• Nondeterministic Turing machines
• The machine may proceed according to several
  possibilities
• Enumerators
• The machine has a printer, i.e. it can add a
  string to the list
• Equivalents
• Other models of general-purpose computation may
  be equivalent to Turing machines if they satisfy
  reasonable requirements

12
Church-Turing Thesis

• Also known as Turings Thesis
• A Universal Turing Machine can perform whatever
  tasks a human computer can achieve when
  following an effective method by rote.
• This thesis provides the definition of an
  algorithm and shows equivalence to the Turing
  machine
• Intuitive Notion of Algorithms
• Turing Machine Algorithms
• Turing machine is a human computer following an
  effective method

13
Consciousness

• Consciousness has been described as a general
  term consisting of 4 categories
• Phenomenal consciousness (P-consciousness)
• Access consciousness (A-consciousness)
• Self-consciousness (S-consciousness)
• Monitoring consciousness (M-consciousness)
• Block, N. (1995).
• On a confusion about a function of consciousness.
  
• Behavioral and Brain Sciences, 18, 227-247.

14
Consciousness

• Phenomenal consciousness
• P-consciousness is experience. The totality of
  the experiential properties of a state are what
  it is like to have it. Includes states when we
  see, hear, smell, taste and have pains.
  Properties of sensations, feelings and
  perceptions, including thoughts, wants and
  emotions
• Access consciousness
• A-conscious, if, because of having the state, a
  representation of its content is
• (1) inferentially promiscuous, i.e., poised to be
  used as a premise in reasoning,
• (2) poised for rational control of action
• (3) poised for rational control of speech

15
Consciousness

• Self-consciousness
• S-consciousness is the possession of the concept
  of the self and the ability to use this concept
  in thinking about oneself
• Monitoring consciousness
• M-consciousness corresponds to at least three
  notions in the literature inner perception,
  internal scanning, and so-called higher order
  thought
• s is a conscious mental state at time t for agent
  a in s is accompanied at t by a higher-order,
  noninferential, occurrent, assertoric thought s'
  for a that a is in s,
• where s' is conscious or unconscious

16
Consciousness Conclusions

• Copelands conclusions on computation
• Since there are limits to the class of problems
  that can be performed by the Turing machine,
  there are limits to what can be accomplished by
  any machine that works in accordance with
  effective methods
• Not all machines need to follow these rules
• It is an open Imperial call question whether
  non-Turing compatible processes are involved in
  the operation of the brain and hence whether a
  computer can simulate all human behaviour

17
Timescales

• Retina ten million detections per second
• 1 MIPS (million instructions per second) Current
• 1,000 MIPS - Snail
• 300,000 MIPS - Mouse
• 10 Million MIPS - Monkey
• 300 Million MIPS - Humanlike