Contents of the DELTA42.DOC file
a Knowledge Acquisition and Inference Tool
This document contains all the information needed to use
DELTA-42. It is the actual manual, there are no hidden
clauses or strings attached. It has been designed to get you
up, running, and creating your own production systems in
very little time. It does not, however, contain a detailed
description of DELTA-42 source code nor pretend to be a
comprehensive tutorial on Expert Systems. Registered users
can receive updates and information concerning the
development of THETA, ALPHA, BETA, and GAMMA. Details on
registering are in the last section titled registration
(C) Copyright ZUMA-1 Software Productions 1988
All Rights Reserved
DELTA-42 is copyrighted. Even though the program is shareware,
and can be freely copied, there are still some limitations to
protect the quality of the distribution of the program and to
support future development, also we have to protect ourselves.
Therefore, we have been advised to include the following:
1].. Users of DELTA-42 may make copies of this program for
trial use by others on a PRIVATE NON-COMMERCIAL BASIS.
2].. By accepting and using this software, you acknowledge
that this software may not suit your particular requirements
or be completely trouble-free.
3].. With proper application, this software will perform as
described. However, ZUMA-1 is not responsible for your
specific application or any problems resulting from use of
4].. If the software does not perform as described, our
liability to you is limited to replacing the software or
refunding the purchase price (if purchased and registered).
We have no liability to you or any other person or entity
for any damage or loss, including special, incidental, or
consequential damages, caused by this software, directly or
indirectly. Some states do not allow the limitation or
exclusion of liability for incidental or consequential
damages, so the above limitation or exclusion may not apply
5].. This Agreement is governed by the laws of the State of
Arizona. Should any part of this agreement be held invalid,
the remainder of the Agreement will still be in effect.
This Agreement can only be modified by written statement
signed by Dallas S. Teat.
Under this license, you may NOT:
A]...Distribute the program in connection with any other
product or service, or as part of a corporate or
institutionally sponsored distribution. Site licenses and
bundling agreements are available upon request. Special
aggreements are made for proven educational institutions.
B]...Charge anything for DELTA-42. An exception is made for
registered user groups who may charge a cost-based fee (not
to exceed $5) to cover their own costs.
C]...Distribute the program in modified form.
D]...Copy or reproduce the printed documentation in any
What is DELTA-42?
DELTA-42 is the next revision for the DELTA-4 program. It features
the addition of CERTAINTY FACTORS. Certainty Factors represent the
confidence you have in a condition. The chart below shows the Certainty
Factors used in DELTA-42:
-1 -.5 0 +.5 +1
least don't most
certain know certain
The numbers range from -1, indicating definite evidence that
a condition is false, to +1, indicating that a condition is definitely
true. Certainty Factors are NOT probabilities. They are informal
measures of confidence or certainty for a condition. They represent
the degree to which we believe that the condition is true in any
To clarify Certainty Factor uses in DELTA-42, consider the
following portion of a rule base:
IF: [ condition ] = 'true' then (certainty factor .6)
IF: [ condition ] = 'true' then (certainty factor .5)
THEN: [ action ] (certainty factor .8)
LEVEL OF CERTAINTY: (final certainty)
This is what happens;
When the first condition is found true, the certainty factor, (.6)
is placed in working memory. Next, when the second condition is also
found to be true, this certainty factor, (.5) is combined with the
first to generate a resulting certainty factor of (.8). The new
certainty factor is next coupled with the certainty factor for the
action (.9) yielding the final certainty (.72).
0 +.5 +1
First CF (.6) -> *
Second CF (.5) -> *
0 +.5 +1
Resulting CF (.8) -> *
0 +.5 +1
CF of [action] (.9) *
Final CF (.72) -> *
As more positive information emerges, then the combined certainty
becomes more definate. On the other hand, indefinate information will
never accumulate to yield a definate conclusion. The order in which
information is combined does not matter. Premises are evaluated
differently depending on the number of clauses and logical connectives
they contain. The actual mechanism for dealing with certainty factors
in DELTA-42 is much more elaborate and extensive. However, this should
explain enough to begin using them. If more information regarding the
application of certainty factors within DELTA-42, please call or write.
Using DELTA-4 Rule Bases with DELTA-42
The utility 'DCONVERT' included with this package, will allow
you to use any DELT-4 Rule Base with DELTA-42. This will eliminate
having to re-enter the rules. From the DOS prompt, simply type: DCONVERT.
You will be asked to supply the name of the DELTA-4 rulebase[.RDB].
Then asked for a name for the resulting DELTA-42 rulebase[.DDB].
All Certainty Factors for the [.DDB] rulebase are set to a default value
of +1.0. To set the factors to indicate your values, load the [.DDB]
rulebase into DELTA-42 and execute the 'ALTER' command.
Like the DELTA-4 program (4/88), the DELTA-42 system (12/88)
is essentially the framework for building a rule-based production
system. DELTA-4 impliments forward chaining inference procedures
with simple propositional production rules. These rules are then
generated into a complete, "stand alone" system in either C or
Pascal source code.
There are three advantages of generating compilable code;
1].. The source code can be tailored to your indivual
compiler. You may chose to add such features as color or
2].. A stand alone module allows for various levels of
computer expertise. Users don't have to learn the DELTA-42
environment to run a system.
3].. The compiled program allows for data integrity and
security. The rules can only be altered by re-entering the
Rule Base into the DELTA-42 environment.
In order to solve a problem, the user simply invokes that
particular .COM or .EXE file and answer the prompts. The system will
then attempt to find the solution based on the answers. It will
chain forward through the rules one-by-one until either one is
proven or none remain. If the programmer, or Knowledge Engineer has
prepared his data sufficiently, there will always be an action to
In DELTA-42, a fact, or condition, is represented simply as a
string, such as "Is it broken?", which must be either true or false,
there are no variables. An action-to-take is a single string
specifying a conclusion that the system is trying to reach. Forward
chaining takes place and the system will try each top-level
condition in order from the beginning of the Rule Base.
The organization of the Rule Base is the key to DELTA-42's
operation. Each rule consists of a series of conjoined conditions
(no disjunctions are allowed), and a single action. Although there
are no certainty factors, the production rules are assumed to be in
"priority order", such that the most desirable conclusions are
You invoke DELTA-42 by keying this at your system prompt.
The DELTA-42 screen is divided into two areas;
The top window (Window-1), where operational menus, program
prompts, and error messages are displayed.
The bottom window (Window-2), where the bulk of your work
will be done.
After the initial DELTA-42 message is displayed, you will see the
operational menu in Window-1. It looks like this:
Working with: Default rule base
Available Commands ->
Create, Load, Save, Alter, Generate, Teach, Erase, Quit,
Summary of Commands:
CREATE........ initializes a new rule base. Use it only when
you are about to CREATE a new rule base.
LOAD.......... reads a rule base from disk into working
SAVE.......... writes a rule base to disk for future use.
You should always Save your rule base in the event that you
may want to add to or change the rules at some future date.
ALTER.......... allows you to look at the rules and the
Certainty Factors one set at a time. ALTER has a sub-menu
that lets you enter 'N' to see the next rule in the list,
or 'X' which displays the current state of all rules which
were True of False up to that point and returns you to the top
level menu, or 'H' for help. Pressing 'H' will provide you
with help on entering or altering Certainty Factors.
GENERATE...... automatically creates the source code needed
to compile a separate module. GENERATE also has a sub-menu
in which you have the option of selecting PASCAL code, or C
code. The code is written to a disk file and can be listed,
printed, edited, or compiled directly.
TEACH......... how the system learns new conditions and
actions. DELTA-4 will prompt you for the neccessary input.
ERASE......... clears the working area of Window-2.
QUIT.......... exits DELTA-42 and returns to DOS.
HELP.......... produces a summary of these commands on the
Creating production systems with DELTA-42 has been simplified as
much as possible. The system will prompt you for input data and warn
you of most errors. The logic involved with designing your rules is
left entirely up to you. We suggest creating a tree type structure
on paper, or even using a flowchart type of visual diagram in order
to determine the hierarchy of your rules.
Included with this program is a small system that is used to
demonstrate how to enter and use Certainty Factors. We feel that an
actual, practical example is a better way to demonstrate just what a
production system can be used for.
Load in the example system and try the commands. It shouldn't
take you long to become familiar with the workings of DELTA-42.
The Brain Theives
DELTA-4 was the first of a set of interrelated Artificial
Intelligence / Expert System programs called The Brain Thieves. All
of the programs will be based on a common concept and relational in
nature. This way as applications increase, the ability to manage
them increases without abandoning any software tools in the set. The
other programs in the set include; THETA, ALPHA, BETA, and GAMMA.
Features of these programs range from certainty factors and fuzzy
logic, through explanation facilities and probability factors, to
object oriented programming and semantic nets.
DELTA-4 & DELTA-42 is distributed through a unique marketing
approach called shareware. The diskette with programs on it can be
freely copied and shared. It is also available from us, at ZUMA-1, for
$15.00 (shipping and handling included). We ask you to help us
distribute DELTA-42 by sharing unmodified copies of the diskette with
others. We also encourage you and those to whom you have
distributed the program to register your copy. Registration has a
number of benefits to you:
1) We would like to make contact with other AI/Expert System
software authors and exchange ideas/programs.
2) Options to beta test the most recent version of the
3) Automatic notice of new programs.
4) Applications support available by phone or mail.
5) Documentation on Expert Systems Applications.
6) Have custom features added.
If you purchased DELTA-42 directly from ZUMA-1 Software
Productions in your own name, then your copy is already registered
and you will recieve all the benefits of registration. You do not
need to send in a registration form.
If you received DELTA-42 some other way, you may register your
copy by filling out the following form and mailing it to the listed
address along with $15.00 (shipping & handling included). You will
promptly receive the latest version of DELTA-4. We will also place
you on our update list so that you will automatically be notified
of any DELTA-42 updates.
ZUMA-1 is a very small, very new organization, and as a result
we don't have any E-mail services yet. We have to rely on the good
old U.S. Mail and various BBS's to make contact. So please take the
time to fill out the registration form and mail it to us. We would
appreciate the feedback. Thank you.
Even if you can't send anything, we would like your comments.
Dallas S. Teat
Zuma-1 Software Productions
1715 West Saint Moritz Lane
Phoenix, Arizona 85023
How did you first learn about DELTA-4/42 or where did you first
obtain a copy of DELTA-4/42?
Any comments or suggestion?