STUDY OF DENDRAL

DENDRAL

AN EXPERT SYSTEM

BY : LAKSHIT GERA

PARTS OF DENDRAL

WHAT IS AN EXPERT SYSTEM ?

PLAN GENERATE TEST PARADIGM

WHAT IS DENDRAL ?

index

WHY IT WAS NEEDED ?

KNOWLEDGE ENGINEERING

HISTORY

DERIVED SYSTEMS

HEURISTIC

What is an Expert System?

In artificial intelligence, an expert system is a computer system that emulates the decision making ability of a human expert.

The first expert systems were created in the 1970s and then proliferated in the 1980s.

What is Dendral?

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

The name Dendral is a portmanteau of the term "Dendritic Algorithm

It was written in Lisp (programming language), which was considered the language of Al because of its flexibility

Mass Spectrum:

Why it was needed?

A mass spectrum is a plot of the ion signal as a function of the mass to charge ratio.

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

Inventors

It was done at Stanford University by Edward Feigenbaum, Bruce G. Buchanan, Joshua Lederberg, and Carl Djerassi. It began in 1965 and spans approximately half the history of Al research

History

During the 20th century, the question "Can Machine think??" became popular among scientists

help him in his exobiology research. Specifically, he was interested in designing computer systems that to help him study alien organic compound

Also around mid 20th century, science, especially biology, faced a fast increasing need to develop a "man computer symbiosis", to aid scientists in solving problems.

Feigenbaum was an expert in programming languages and heuristics, and helped Lederberg design a system that replicated the way Carl Djerassi solved structure elucidation problems.

In the early 1960s, Joshua Lederberg started working with computers and quickly became tremendously interested in creating interactive computers to

They devised a system called Dendritic Algorithm (Dendral) that was able to generate possible chemical structures corresponding to the mass spectrometry data as an output

The Dendral team recruited Bruce buchanan to extend the Lisp program initially written by Georgia Sutherland.

Heuristics

The use of heuristics to solve problems is called "heuristics programming", and was used in Dendral to allow it to replicate in machines the process through which human experts induce the solution to problems via rules of thumb and specific information.

Heuristics programming was a major approach and a giant step forward in artificial intelligence, as it allowed scientists to finally automate certain traits of human intelligence.

As Herbert A.Simon said in The Sciences of the Artificial, "if you take a heuristic conclusion as certain, you may be fooled and disappointed; but if you neglect heuristic conclusions altogether you will make no progress at all."

PARTS OF DENDRAL

HEUSTRIC DENDRAL

META DENDRAL

Heuristic Dendral

Meta Dendral

Meta Dendral is a machine learning system that receives the set of possible chemical structures and corresponding mass spectra as input, and proposes a set of rules of mass spectrometry that correlate structural features with processes that produce the mass spectrum.

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

A mass spectrum of a compound is produced by a mass spectrometer, and is used to determine its molecular weight, the sum of the masses of its atomic constituents.

These rules would be fed back to Heuristic Dendral (in the planning and testing programs described below) to test their applicability

Plan generate test paradigm

The generator (later named CONGEN) generates potential solutions for a particular problem, which are then expressed as chemical graphs in Dendral. However, this is feasible only when the number of candidate solutions is minimal. When there are large numbers of possible solutions, Dendral has to find a way to put constraints that rules out large sets of candidate solutions.

The plan generate test paradigm is the basic organization of the problem solving method, and is a common paradigm used by both Heuristic Dendral and Meta Dendral systems.

Knowledge Engineering

The primary aim of knowledge engineering is to attain a productive interaction between the available knowledge base and problem solving techniques

This is possible through development of a procedure in which large amounts of task specific information is encoded into heuristic programs. Thus, the first essential component of knowledge engineering is a large "knowledge base."

This "knowledge base" is used both to search for possible chemical structures that match the input data, and to learn new "general rules" that help prune searches.

Derived Systems

Many System were derived from Dendral including

MACSYMA

MOLGEN

MYCIN

PROSPECTOR

XCON

STEAMER

Thank you all