Lecture 8: Expert system shells

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Lecture 8Expert system shells
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Building expert systems

• If one wishes to build an expert system, one has
  several choices of software tool
• (1) conventional programming languages (e.g.
  Pascal, C, Java)
• (2) artificial intelligence programming
  languages (particularly LISP and Prolog)
• (3) expert system shells

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Building expert systems

• The first choice is almost certainly a bad idea.
• Conventional programming languages are not
  designed for this sort of job, and too much work
  is required to make the program perform in the
  way required.
• However, if it is important to have highly
  efficient software, this might be a suitable
  choice.

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Building expert systems

• Choice (2) has the advantage
• a flexible system can be built, accurately
  reflecting the peculiarities of the knowledge
  domain and system task.
• and the disadvantages
• Programming skills in these languages are not
  common. It may be necessary to hire specialist
  programmers, or retrain the programming staff.
• Programming the system will always be a larger
  (and hence longer and more expensive) task than
  using a shell.

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Building expert systems

• Choice (3) has been the most frequent choice for
  commercial systems in recent years.

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Building expert systems

• You will remember that an expert system shell is
  a ready-made expert system, with the
  knowledgebase missing, together with instructions
  for building a knowledgebase in the customer's
  chosen domain.

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The idea of an e.s. shell
User Interface
Inference Engine
Knowledgebase on blood infections
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The idea of an e.s. shell
User Interface
Inference Engine
Knowledgebase on chest infections
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The idea of an e.s. shell
User Interface
Inference Engine
Knowledgebase on skin diseases
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Shells

• Some organisations avoid using shells for
  building complete expert systems but even they
  frequently use them for
• training
• building prototypes

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Expert system programming environments

• Some people make a distinction between e.s.shells
  and e.s.programming environments (or "hybrid
  systems"). For instance, Efraim Turban does in
  his book (Turban, 1992).

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Expert system programming environments

• Historically, this has been important because, in
  the 1980s, most expert systems projects in the UK
  used shells (as described below), and most expert
  systems projects in the USA used environments.

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Expert system programming environments

• Environments were so called because they provided
  several different forms of knowledge
  representation, for instance,
• rules
• metarules
• frames
• semantic nets
• and several different forms of inference, e.g.
• forward chaining
• backward chaining
• bidirectional chaining
• non-monotonic reasoning

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Expert system programming environments

• They needed more powerful hardware than a
  microcomputer - usually, a workstation.Historical
  ly, e.s. shells have been more constrained,
  perhaps offering only a single kind of knowledge
  representation. They would usually be designed to
  run on a PC.

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Expert system programming environments

• However, in recent years,E.S.shells have become
  more sophisticated, and added multiple forms of
  knowledge representation and of inference
  strategy.PCs have become more powerful, and PC
  versions of e.s.environment software have been
  released.

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Expert system programming environments

• It is probably not useful to make the distinction
  any more. One could simply speak of "simple
  shells" and "sophisticated shells".

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Advantages and disadvantages of expert system
shells

• AdvantagesThe programming effort that has gone
  into building the user interface and inference
  engine is re-used.

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Using a shell advantages

• Advantages
• The level of programming skill needed to produce
  the finished system is much lower than it would
  be if the system was programmed from scratch
  using a language.
• This means that, if an appropriate shell is
  chosen, the project can be completed faster, and
  cheaper.

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Using a shell disadvantages

• Disadvantagese.s.tools are "end-user tools".
  Compared with systems programmed from a language,
  such software packages tend to produce systems
  that have
• poor documentation
• weak security
• difficult maintenance problems

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Using a shell disadvantages

• Disadvantagesthe problem of flexibility
• If the shell is a poor match for the type of
  knowledge in the domain concerned, it is liable
  to produce a system which simply doesn't
  correspond to the expertise of the original
  domain expert

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Using a shell disadvantages

• In an attempt to model a non-standard piece of
  reasoning, the system builders may produce a
  "system" which consists of two or more expert
  system shells side by side. Such a "system" is
  bound to be unsatisfactory, and to lead to
  problems of use, maintenance and training.

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The problem of flexibility

• The principle underlying the expert system shell
  is that a knowledgebase can be removed from an
  expert system, another can replace it, and the
  system will reason just as effectively with the
  new knowledge as with the old.

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The problem of flexibility

• This assumes that the same inferencing techniques
  are used by every expert, and in every domain.

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The problem of flexibility

• In fact, there is evidence that
• Different experts use different problem-solving
  skills
• Different types of problem-solving task require
  different types of reasoning.

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The problem of flexibility

• "...it must be established that the logic and
  reasoning method incorporated in the shell
  correspond to those used by the human expert in
  problem solving, otherwise the project is almost
  certainly doomed to failure." Ian Graham, in
  Forsyth (1989), p.81

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Factors involved in choosing a shell, or other
software tool, for an e.s. project

• 1. The characteristics of the knowledge, and the
  style of inference, used by the domain expert or
  experts.2. The time and money available for the
  project.3. The programming capabilities
  available in-house (what languages do the
  programmers know? Is it feasible to retrain
  them?).

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Factors involved in choosing a shell, or other
software tool, for an e.s. project

• 4. The hardware available for development.5.
  The hardware the system will eventually run
  on.6. The required performance of the system.

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Factors involved in choosing a shell, or other
software tool, for an e.s. project

• The selection procedure should involvea)
  Doing enough knowledge acquisition to establish
  (1).b) Deciding whether shells are available
  whose inference strategies and knowledge
  representation match the requirements of the
  problem. If not, is the skill available to treat
  this as a job for programming in a computer
  language?

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Factors involved in choosing a shell, or other
software tool, for an e.s. project

• c) Establishing that software suggested by
  stage (b) will run on the available hardware, and
  provide adequate performance in terms of speed,
  etc.
• d) Establishing that sufficient time and money
  is available for the project.

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Factors involved in choosing a shell, or other
software tool, for an e.s. project

• e) Establishing that any shell still under
  consideration has the capabilities required by
  the project.
• Has it got adequate explanation facilities?
• Can it handle a large enough knowledgebase?
• Can it interface easily with other pieces of
  software which are to be used by the finished
  system?

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Factors involved in choosing a shell, or other
software tool, for an e.s. project

• These questions should decide whether the project
  is viable at all and, if it is, which shell, or
  AI language, or conventional language, is the
  appropriate tool for the job.

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Example of an up-to-date PC shell Acquire SDK

• Acquire SDK is marketed by a Canadian software
  house (Acquired Intelligence Inc) as one of a
  range of expert system tools.The
  knowledge-representation involves objects (as
  used in object-orientated programming these are
  conceptually very similar to frames) combined
  with rule-based reasoning.

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Example of an up-to-date PC shell Acquire SDK

• Product description, and testimonials, taken from
  their web site (Nov.2001)

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Example of an up-to-date PC shell Acquire SDK

• The Acquire Software Development Kit (SDK) lets
  you integrate the Acquire inference engine and
  knowledge bases into your applications. You can
  build intelligent applications using many popular
  development environments -- including Visual
  Basic, Visual C, Java, Delphi, PowerBuilder,
  ToolBook -- or any other development environment
  that supports ActiveX controls or DLL function
  calls.

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Example of an up-to-date PC shell Acquire SDK

• Acquire SDK 2.1 lets you operate multiple
  knowledge bases simultaneously within a single
  application, and lets many users access the same
  knowledge base at the same time.
• Under special arrangements, the Acquire SDK
  libraries are available for SCO Unix, Sun OS,
  Solaris, and Linux, and can be ported to almost
  any Unix variant.

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Example of an up-to-date PC shell Acquire SDK

• Easy to use -- you can build a
  full-featured intelligent application in Visual
  Basic with just a handful of statements.
• The inference engine generates events when
  a rule fires, when a conflict occurs, or when it
  needs additional information.
• Ability to utilize multiple knowledge bases
  simultaneously in one application.
• Ability to deliver client/server
  applications.

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Example of an up-to-date PC shell Acquire SDK

• Includes sample applications that show you
  how to build WWW applications with CGI or Java.
• Ability to access the contents of knowledge
  bases, including messages written by the
  knowledge base author that can be used to give
  situation-specific commands to your application,
  and permitting customization from within the
  knowledge base.

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Example of an up-to-date PC shell Acquire SDK

• Flexibility of data source obtain input
  interactively from the user, from the knowledge
  base, from a database or spreadsheet, or from a
  hardware device or other source.
• The expert system is embedded - the user
  needn't be aware that an expert system is being
  used at all.

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Example of an up-to-date PC shell Acquire SDK

• When we first discussed the possibility of an
  expert system in neuropsychology, I thought it
  was an interesting, albeit impossible idea. Now
  that I have used ACQUIRE to build two different
  knowledge bases (in neuropsychology and school
  psychology) I am looking forward to building
  other applications for my clinical practice.
• Dr. Diane Russell, Neuropsychologist

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Example of an up-to-date PC shell Acquire SDK

• Radio interference is a complex, diagnostic
  problem that all countries have. Using ACQUIRE
  has allowed us to build a huge, comprehensive and
  complex knowledge base (The Radio Interference
  Advisor) that is so well structured that it is
  very easy to understand, use and maintain. It
  usually takes up to three years to teach a new
  technician to be a radio inspector.

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Example of an up-to-date PC shell Acquire SDK

• Once trained as a radio inspector, solving
  particularly difficult radio interference
  problems (e.g., intermodulation products) can
  still be very labour intensive. We are using this
  as a tool to speed up both the training process
  and the diagnostic process. It is an
  extraordinary learning tool, so it can also be
  used in the classroom.

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Example of an up-to-date PC shell Acquire SDK

• We've been finding new applications for the
  software even before it's finished.
• Dave Sinclair
• Operations Manager, Spectrum
• Industry Canada (Retired)

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Example of an up-to-date PC shell Acquire SDK

• MacMillan Bloedel is using the powers of
  ACQUIRE to assist personnel in machine startup
  and to help diagnose machine breakdown. One of
  the greatest strengths of this product is that it
  is designed for the expert to build his/her own
  knowledge base.

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Example of an up-to-date PC shell Acquire SDK

• Bypassing the requirement of a knowledge engineer
  can significantly reduce the project costs and
  lower the risk of misinterpreted information. In
  addition, ACQUIRE operates on a PC platform,
  eliminating the need to purchase specialized
  computer equipment.
• Sharlene Yap
• Computer Scientist, Wood Harvesting
• MacMillan Bloedel Research Corp.

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Example of an up-to-date PC shell Acquire SDK

• The ACQUIRE knowledge acquisition system is
  the underlying technology for an intelligent
  tutoring system for crew training. The resultant
  system, ACQUIREITS, inherits the benefits of
  ACQUIRE while providing the tools with which the
  general PC user can develop and maintain their
  own intelligent tutoring applications.
• Canadian Space Agency

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Example of an up-to-date PC shell Acquire SDK

• Analysing international trade in commodities and
  forecasting market prices are particularly
  difficult tasks. Each market differs
  considerably, and the trader or analyst must
  develop detailed knowledge of his/her specialist
  area. Mathematical modeling is often unsuccessful
  because it fails to represent this knowledge
  adequately, especially that relating to the

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Example of an up-to-date PC shell Acquire SDK

• nonquantitative factors which affect commodity
  markets. ACQUIRE allowed us to rapidly model an
  important and complex commodity market (for
  Soybeans), paying attention to the psychological
  elements of "market sentiment". The resulting
  system, SoyTrader, incorporates a number of rules
  which make it a considerable advance on other
  formal models of this

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Example of an up-to-date PC shell Acquire SDK

• market. ACQUIRE allowed us to prototype
  SoyTrader quickly, and to achieve impressive
  forecasting results results which other analysts
  had doubted were possible.
• Geoffrey Bastin
• Economist, MIL, London, U.K.

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Examples

• One piece of knowledge represented in three
  rule-based shells.
• Original knowledge, elicited from the domain
  expert (a salesman for life assurance products)

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• "Suppose the customer has a lump sum to invest,
  and they want to see some growth in the
  investment. Suppose also that they do want a
  pension, but don't need life cover. In that case,
  I'd advise them to buy an annuity.

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Example Crystal

• This knowledge represented in Crystal
• Annuity
• IF lump sum to invest
• AND growth desirable
• AND pension needed
• AND NOT life cover needed
• AND conclusion display

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Example Leonardo

• This knowledge represented in Leonardo
• 1 if investment is 'lump sum'
• 2 and growth is desirable
• 3 and pension is desirable
• 4 and life.cover is unnecessary
• 5 then advice is annuity

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Example Leonardo

• Object number 2g
• 1 Name investment
• 2 Type
• 3 Certainty
• 4 Default value
• 5 Allowed value regular, lump sum
• 6 Compute value
• 7 Query prompt What kind of payment are you
  prepared to make?

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Example Leonardo

• 8 Query preface
• We have to establish first whether you wish to
  save regularly or merely invest a single lump
  sum. Later we may explore a combined approach.
• - NB there are 18 slots in an object frame.

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Example Guru

• This knowledge represented in Guru
• RULE R1
• IF INVESTMENT "lump sum" AND
• GROWTH "desirable"
• AND PENSION "desirable" AND
• LIFECOVER "unnecessary"
• NEEDS INVESTMENT,
• LIFECOVER, GROWTH, PENSION
• THEN ADVICE "annuity"

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Example Guru

• REASON For someone who wants capital growth and
  a pension but has no need of life cover, the best
  use of a lump sum is the purchase of a deferred
  annuity.