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Dendral Expert system

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Presented By:

Group No:-2

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OUTLINE

1. Meaning of Dendral2. Inventors3. History4. Heuristic Dendral5. Meta Dendral6. Working7. Plan-test-generate paradigm8. Knowledge engineering9. Disadvantages10. Conclusion

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Dendral was an influential pioneer project inartificial intelligence (AI) of the 1960s, and the computer software expert system that it produced.

The name Dendral is a portmanteaux of the term “Dendritic Algorithm“

Its primary aim was to help organic chemists in identifying unknown organic molecules, by analyzing their mass spectra using knowledge of chemistry.

Meaning of Dendral

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Inventors:

It was done at Stanford University by Edward

Feigenbaum, Bruce Buchanan, Joshua

Lederberg (a Nobel prize winner in genetics) and Carl Djerassi. It began in 1965 and spans

approximately half the history of AI research.

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It was written in Lisp (programming language), which was considered language of AI. (john McCarthy, 1958, MIT)

For this in laboratory, three generate and test 'method was used:-

(possible hypothesis about molecular structure are generated and tested by matching to actual data).

There was an early realization that experts use certain heuristics to rule out certain options with possible structures.

It seemed like a good idea to encode that knowledge in a software system

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The software program Dendral is considered the first expert system because it automated the decision-making process and problem-solving behavior of organic chemists.

DENDRAL marked a major paradigm shift´ in AI: a shift from general AI: a shift from genera-- Purpose, knowledge purpose, knowledge-- Sparse weak methods to domain sparse weak methods-- Specific, knowledge-- Intensive techniques intensive techniques

History

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The aim of the project was to develop a computer program to attain the level of computer program to attain the level of performance of an experienced human chemist.

The DENDRAL project originated from the fundamental idea of Expert system

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Dendral

It consists of two sub-programs:

Heuristic-Dendral

Meta-Dendral

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Heuristic Dendral

Heuristic Dendral is a program that uses mass spectra with knowledge base of chemistry, to produce a set of possible chemical structures that may be responsible for producing the data.

. As the weight increases the molecules become more complex, the number of possible compounds increases drastically.

(Example: H2O)

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Meta-Dendral

Input - 1) The set of possible chemical structures 2) Corresponding mass spectra

Output- Explain correlation between proposed structures & mass spectrum. Thus, Heuristic Dendral is a performance system Meta Dendral is a learning system. The program is based on two important features: 1) the plan-generate-test paradigm 2) knowledge engineering.

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WORKING

Heuristic Dendral

Meta Dendral

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PLAN – GENERATE - TEST PARADIGM

It is a problem solving method used by both M.D. & H.D.

Aim-When there are large number of possibilities at that it find a way to put constraints that rules out large sets of candidate solution.

“Hypothesis Formation Programe”

“Task specific knowledge”04/12/2023

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EXAMPLE-CONGEN

Available Information- C1: Empirical Formula- C12H14O. C2: Compounds Contains Keto group. C3: Three protons to the carbonyl group. C4: There are two vinyl group. C5: There is no conjugation. C6: There are no diallylic protons. C7: There are no additional multiple bonds. C8: There are no methyl group.

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PROCEDURE

#DEFINE MOLFORM C12H14O. #DEFINE SUBSTRUCTURE Z #DEFINE SUBSTRUCTURE CH3.

#DEFINE SUBSTRUCTURE V. #GENERATE #DRAW ATNAMED1 #AMBEDED #DRAW ATNAMED1 . . . #EXIT 04/12/2023

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FINAL OUTPUT

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KNOWLEDGE ENGINEERING

Aim- To attain a productive interaction between the available knowledge base & problem solution techniques.

The first essential component of K.E. is “knowledge base”.

It is used to determine the set of possible chemical structures that corresponds to the input data

& form new general rules that helps it reduce the number of candidate solutions.

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Derived systems:

Many systems were derived from Dendral, including:-

1. MYCIN

2. MOLGEN

3. MACSYMA

4. PROSPECTOR

5. XCON, and STEAMER

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It is a system that does not guarantee about the solution, but reduces the number of possible solution by discarding unlikely & irrelevant solution.

Conclusion

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References:

Wikipedia

E-book

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Any Queries

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