This directory contains the hol90 UNITY library, due to Flemming Andersen.

The library defines the basic temporal operators in the (full-state) UNITY
logic [K. Chandy, J. Misra: Parallel Program Design -- A foundation] and
contains theorems corresponding to the properties of these.

The installation guide below should be performed when installing the hol90
system.  Hence, if the hol90 command

	- known_libraries();

indicates that the unity library has been declared you may skip this step.

To use the library follow the instructions in Loading Guide.


Installation Guide:
------------------

  The UNITY library creates a hiearchy of theories grounded in the HOL
theory.  These theories will be build by invoking the shell command:

	% make_unity [hol90]


Next the UNITY library should be declared to hol90. This is already done
in the hol90 building process: see src/3/sys_lib.sml.


Loading Guide:
-------------

  The UNITY library is loaded by the hol90 library command:

	- load_library{lib= unity_lib, theory= <name>};

The <name> of the theory is up to the user. One can also use 
"load_library_in_place", if already in draft_mode.

Note (kls). In a compiled regime, the code for this library must be
compiled with the theory "leadsto" in the ancestry.
