

GEOTHER (GEOmetry THeorem provER) is an environment implemented by
Dongming Wang
in Maple with drawing routines and interface written previously
in C and now in Java for manipulating and proving geometric theorems.
In GEOTHER a theorem is specified by means of predicates of the form
Theorem(H,C,X)
asserting that H implies
C, where H
and C are lists or sets of predicates
that correspond to the geometric hypotheses and the conclusion of the
theorem, and the optional X is a list
of variables used for internal computation. The information contained
in the specification may be all that is needed in order to manipulate
and prove the theorem. From the specification, GEOTHER can
automatically
 assign coordinates to each point in some optimal manner;
 translate the predicate representation of the theorem into
an English or Chinese statement, into a firstorder logical formula,
or into algebraic expressions;
 draw one or several diagrams for the theorem  the drawn
diagrams may be animated and modified with a mouse click and dragging,
and saved as PostScript files;
 prove the theorem using any of the five algebraic provers;
 translate the generated algebraic nondegeneracy conditions
into geometric/predicate form;
 generate an HTML, LaTeX, and/or PostScript file documenting
the theorem and its proof.
The assignment of coordinates to points can be done optionally
by the user. The algebraic provers are based on Wu's method,
the Gröbner basis method, and a method proposed by D. Wang.
GEOTHER can run with a menudriven graphic user interface and
contains a collection of theorems in both elementary and
differential geometries with sample specifications that have
been proved. These proved theorems include those named after
Steiner, Morley, Thébault, MacLane, and Bertrand. The package
also has functions for handling the collection of theorems
and online help for all functions with examples.
Excerpts with modification from Mathematics Mechanization and
Applications, Academic Press, pp. 495496 (2000).
Last Modification: June 18, 2003