1. Meaning of Dendral
4. Heuristic Dendral
5. Meta Dendral
7. Plan-test-generate paradigm
8. Knowledge engineering
Dendral was an influential pioneer project inartificial intelligence
(AI) of the 1960s, and the computer software expert system that it
The name Dendral is a portmanteaux of the term
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
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.
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
The software program Dendral is considered the first
expert system because it automated the decision-making
process and problem-solving behavior of organic
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
-- Specific, knowledge
-- Intensive techniques intensive techniques
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
The DENDRAL project originated from the
fundamental idea of Expert system
It consists of two sub-programs:
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
Input - 1) The set of possible chemical structures
2) Corresponding mass spectra
Output- Explain correlation between proposed
structures & mass spectrum.
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.
PLAN – GENERATE - TEST PARADIGM
It is a problem solving method used by both M.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”
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.
Aim- To attain a productive interaction between the
available knowledge base & problem solution
The first essential component of K.E. is “knowledge
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.
Many systems were derived from Dendral, including:-
5. XCON, and STEAMER
It is a system that does not guarantee
about the solution, but reduces the number of
possible solution by discarding unlikely &