I am pleased to announce the release of version 3.0 Otter.

Here is the abstract from the manual:

Otter (Organized Techniques for Theorem-proving and Effective
Research) is a resolution-style theorem-proving program for
first-order logic with equality.  Otter includes the inference rules
binary resolution, hyperresolution, UR-resolution, and binary
paramodulation.  Some of its other abilities and features are
conversion from first-order formulas to clauses, forward and back
subsumption, factoring, weighting, answer literals, term ordering,
forward and back demodulation, evaluable functions and predicates, and
Knuth-Bendix completion.  Otter is coded in C, is free, and is
portable to many different kinds of computer.

This release is for UNIX-type operating systems.  I have had reports
that a beta version Otter 3 compiles in DOS (Turbo-C and GCC)
and for Macintosh (Think-C) with minor changes to the source.

You can FTP a copy from info.mcs.anl.gov, file
pub/Otter/otter-3.0.0.tar.Z .  Unpack it in the usual way:

   uncompress otter-3.0.0.tar.Z
   tar xvf otter-3.0.0.tar

This will create a directory otter-3.0.0 containing several
subdirectories.  See otter-3.0.0/README for further information.
Send a note to otter@mcs.anl.gov for current information.

When bugs surface and are fixed, patch levels will be released.
The n-th round of bug fixes will be called otter-3.0.n.  The patch
levels are full distributions, so it is nearly always best to fetch
the highest patch level.

   January 1994

 ---------------------------------------------------------------------
 |  William W. McCune              |    e-mail:  mccune@mcs.anl.gov  |
 |  MCS-221                        |    phone:   (708) 252-3065      |
 |  Argonne National Laboratory    |    FAX:     (708) 252-5986      |
 |  Argonne, IL  60439-4844        |                                 |
 |  U.S.A                          |                                 |
 ---------------------------------------------------------------------

Some features new in Otter 3:

In the autonomous mode (Sec. auto), the user simply inputs clauses,
and Otter decides on inference rules and strategies.

The hot list (Sec. hot) can be used to give emphasis to some of the
input clauses.  (Suggested by Larry Wos.)

The user can declare function symbols to be infix with associativity
and precedence so that expressions can be written in a natural way
(Sec. ops).

Clauses can be written in sequent notation (Sec. sequent).  (Suggested
by Art Quaife.)

The new evaluable functions include bit string operations (Sec. eval)
and floating-point operations (Sec. float).

The inference rule gL builds in a generalization principle for cubic
curves (Sec gl).  (Suggested by R. Padmanabhan.)

The user can write in C his or her own evaluable operations
(Sec. foreign).

Given clauses can be selected interactively (Sec. loop-flags).
(Suggested by Bob Veroff.)

Ordered hyperresolution (Sec. misc-flags) has been implemented
(suggested by Mark Stickel) and is the default.

Some optimizations have been implemented for propositional problems
(Sec. misc-flags).

The justification lists for binary resolvents and paramodulants now
tell which literals or terms were unified to produce the clause.

