August 16, 1995.  mace 1.2.0 released

April 1996.  New print option -P, for printing in "portable format",
	which is for reading into another program (eqp semantic para).

	Result is mace-1.2.0a

Sept 26, 1996.
	1.  New option -c, for distinct constants (up to n).
	    This should work correctly with domain elemnts in
	    clauses and special unit assignments, but NOT with -z.
	2.  time limit is checked during generation of prop. clauses
	    (after processing of each FO clause).
	3.  For printing models, "-" changed to "T" in relations.
  
        Result is mace-1.3

July 2, 1997 (in preparation for CASC-14).

	1. bug: crash if arity too great.  fixed.
	2. It used to abend if propositional unsatisfiability was
	   detected in add_clause (e.g., conflicting units).
	   Now, call exit(UNSATISFIABLE_EXIT) in that case.
	Result is mace-1.3.1

Nov 4, 1997.
	Changed MAX_CLAUSES from 100 to 500 (so we could do Dale Myers'
	zebra problem).

Dec 1, 1997.
	Changed tp_alloc_size from 300,000 to 1,000,000 (for M. Spinks prob).
	result it mace-1.3.2.

Dec 7, 1998.  
        1. Bug from Branden Fitelson: When printing relations,
        the nondetermined atoms (atom_value() = 2) should be "F",
        because the propositional engine selects positive clauses,
        and no more positive clauses (the termination condition),
	means that the unassigned atoms should be "F".  The error
	was introduced in mace-1.3 above, item 3.

	2. Increase default max-mem from 16MB to 48 MB.

        result is mace-1.3.3.

June, 1999.
	New command-line option -I to print models in Ivy format.

February, 2000.	

	Release mace-1.3.4

May 16, 2000.
	Bug.  I wasn't checking for symbol table overflow.  Fixed.
	Also, I increased the symbol table size from 50 to 100, so
	it could handle the set problems in TPTP.  (Well, it still
	can't handle the set problems in TPTP, because there is a
	clause with 13 variables.  (Max is 12, and that limit is wired in.)

May 16, 2000.
	Lots of cleaning up, and some reorganization of the code.

------ 2001------ 2001------ 2001------ 2001------ 2001------ 2001

May, first half, 2001.  MAJOR overhaul of MACE, to make it self-contained.
	Now, Otter code (to parse input) is loaded along with MACE.
	This involved lots of soruce code reorganization.
	And there were more than a few changes to the functionality.
	A 9-page "MACE 2.0 User Manual and Guide" was written.
	
May 11, 2001.  Release MACE 2.0-beta as part of Otter-3.2-beta.

May 14, 2001.  Added -N option: ability to iterate through domain sizes.
	This eliminates the need for a separate maceloop program.
	This involved substantial reorganization of the MACE code.
	Updated manual.

May 29, 2001.  Bug (reported by Johan Bos) printing with -P.
	Comma after last printed symbol if equality relation is last.
	Fixed print_models_portable().

May 29, 2001.  Changed Ivy (-I) printing to print equality relations
	other than "=", because "=" is the only equality built-in to Ivy.

June 8, 2001.  Added constraints (when -c is not used) to reduce number
	of isomorphic models w.r.t. constants.  I believe it is complete,
	and it seems to work as well as -c for some examples.
	See iso_constants() in generate.c.  mace-2-beta-4.

June 11, 2001.  Bug if more than 2^16 - 1 (65535) atoms.  Fixed the
	code that does the check.  It now abends.  mace-2-beta-5.

	This is the deadline for CASC-2001 installation, so it got
	this version.

June 12, 2001.  The new iso constraints (June 8) are exponential in
	the number of constants.  Added a new command-line switch:
	-z n says to apply the constraints to the first n constants.
        mace-2-beta-6.

June 14, 2001.  Bug in iso constraints.  Fixed.  Also, separated
	"theory elements" (domain elements in clause list) from
	"constraint elements" (domain elements in mace_constraints list).
	An element can be both theory and constraint (or neither).
	Iso constraints ignores constraint elements when asserting clauses.
	Also, changed -c so that it ignores constraint elements.
        mace-2-beta-8.

July 2, 2001.
	Added option -C to split on clauses.
	Added option -r to print order of assignments for each model.
	mace-2-beta-11.

August 13, 2001.  Release Otter 3.2 and MACE 2.0 for Unix.

June 2003.  Reorganize directories in preparation for the
	Otter 3.3/Mace 2.2 release.

August 4-6, 2003.  At the model-building workshop at CADE-19, I heard
	a talk on mace2-style model searching by Koen Claessen and
	Niklas Sorensson.  There was good evidence that dividing
	flattened clauses to reduce the number of variables pays off well.
	I've known about this method for several years, but I never got
	around to trying it myself, mostly because I've been focusing
	on mace4 (the equational method).
	Anyway, I tried it, and it works well enough to include
	as default in mace2.  The new code is in part.c, and a command-line
	switch -vn (default n=1) says to apply the method to clauses
	with n or more variables.  This changes the searches in most
	of the test problems, so the "official" output files were
	rebuilt.

	This new feature can be disabled with, for example, -v1000.

August 12, 2003.  Bug introduced in Aug 4--6 mods: answer literals
	not removed.  Fixed.  Second minor bug:  if set(process_input),
	clasues don't get IDs.  Fixed.

August 27, 2003.  Increased MAX_SYMBOLS in Generate.c from 100 to 500.

------------------------------------

August 27, 2003.  Freeze for Otter 3.3 / Mace 2.2 release.

