     TwoGroups: a NU-Prolog database for the groups of order dividing 256 
     #################################################################### 


This file describes the steps you should carry out to install and 
execute the TwoGroups database.

Detailed information on the use of the database is provided in the 
user guide and other material supplied in the doc directory.

STEP I - Extraction Stage
-------------------------
Assume that the TwoGroups related files will reside in the directory 
MYPATH/TwoGroups. 

Change directory (cd command) to MYPATH.

Then, uncompress the supplied file 'TwoGroups.tar.Z', and extract its 
contents as follows.

uncompress -v TwoGroups.tar.Z
tar -xvf TwoGroups.tar

This creates a directory called TwoGroups and the directory 
MYPATH/TwoGroups will contain the files:

README (text file)
nep (executable file)
twogroups (executable file)
twogroups.save (executable file)
database (a directory which contains the TwoGroups database files)
doc (a directory containing documentation)

STEP II - Environment Setup Stage 
---------------------------------
You must now define an environment variable TwoGroups by adding the 
following definition to the appropriate (.cshrc or .login) file:

setenv TwoGroups MYPATH/TwoGroups

Also add the $TwoGroups to your path.

The database should now be installed. You may now check that it
executes correctly.

STEP III - Execution Stage
--------------------------

The Prolog environment is entered by typing 'twogroups'
The query language processor is entered by typing 'query.'

To return from the Query to Prolog environment, type 'quit;'
To return from the Query to Unix environment, type 'exit;'

When you first enter the query language environment, the external
TwoGroups database is consulted -- this generates certain warning
messages which should be ignored. 

SAMPLE SESSIONS
---------------
I. Comments: Illustrates how to abort/exit from a Prolog session. 
             1?, ... are NU-Prolog prompts.
-----------------------------------------------------------------
pell% twogroups
NU-Prolog 1.5.24
1?- <Ctrl>C
Prolog interrupted (h for help)? a
Prolog abort.
1?- <Ctrl>C
Prolog interrupted (h for help)? e
pell%


II. Comments: Illustrates how to quit/exit from a Query session.
----------------------------------------------------------------
pell% twogroups
NU-Prolog 1.5.24
1?- query.
Warning: $param/4 redefined
Warning: group_info/11 redefined
Warning: seq/11 redefined
Warning: num_of_classes/4 redefined
Warning: elements_of_order/4 redefined
Warning: auto_gp/4 redefined
Loading MYPATH/TwoGroups/database/.rules.no.
done

input> quit;
Prolog abort.
2?- query.

input> exit;
pell%


III. Comments: A sample session. Shows database load (with warnings)
--------------------------------------------------------------------------
pell% twogroups
NU-Prolog 1.5.24
1?- query.
Warning: $param/4 redefined
Warning: group_info/11 redefined
Warning: seq/11 redefined
Warning: num_of_classes/4 redefined
Warning: elements_of_order/4 redefined
Warning: auto_gp/4 redefined
Loading MYPATH/TwoGroups/database/.rules.no.
done

input> s := {G in database | order(G) eq 4};
Number of solutions in s equals 2

input> print s;
Solutions in s ->
[(4, 1), (4, 2)]
Number of solutions in s equals 2

input> exit;
pell%

Last revised July 1, 1993 
