* Additional problems (including PolyPaver benchmarks), and revisions to problems

* Mathematica can be used as external algebraic decision method

* New parser (built using ML-YACC) with greatly improved error recovery. However, the syntax of cnf is now strictly enforced, so existing problems may need some additional parentheses.

* function "log" (common logarithms) and axiom file log.ax

* Notation for intervals

* Problems with non-disjoint free and bound variables are rejected
  (as probably missing parentheses after a quantifier).

* New option --rerun on/off (Reruns unsuccessful proofs with more liberal search settings)

MetiTarski release 1.9 2011-08-05

* Correction of a soundness bug involving decision procedure calls and labels.
  (Only one false theorem was proved as a result of this bug, namely X2-tan.tptp.)

* Case-splitting with backtracking.

* Heuristic improvements, e.g. SOS weighting, the --maxalg and --proj_ord switches

* Syntactic changes
   - in CNF, negative literals may appear as ~ ( ATOM ) and not just ~ ATOM
   - decimal numbers may start with a decimal point: .1

* Slightly improved documentation in the README file.

* Refinement and corrections to the internal QEPCAD interface.

* The addaxioms script now works with Windows line breaks and spaces at the start of lines.

* Additional problems.

MetiTarski release 1.8 2011-01-18

* Constant folding, to ensure that 1.01, 1 + 10^-2 and 101/100 produce identical terms.

* Experimental case-splitting facility “without backtracking". It is ON by default.

* Significant new heuristics, various small bugfixes and other refinements.

* Complicated new exp, sine and cosine problems.

* Removal of the axiom arctan(0) = 0 and similar axioms for tan, arcsin, cosh, sinh, tanh.
  They were never used in proofs (empirically) but could slow down the search.

* Removal of the constant pi from the axioms for arctan.

MetiTarski release 1.7 2010-11-01

* Corrected a serious parsing bug, ensuring that -X^2 is parsed as -(X^2) and not as (-X)^2!

* Corrected a serious error in the file atan-extended.ax, where the axiom atan_upper_bound_case_41
  did not hold when X=0!

* Added the functions cbrt (cube roots), arcsin and arccos.

* New option --time to limit the processor time used in the proof attempt.

* New option --tstp to generate standard TSTP output with no infixes or minus signs.

* New option --full to include variable instantiations in proofs.

* New bounds for sqrt, using scaling to improve accuracy near zero and for large arguments.
  The old fourth-order bounds have been moved to sqrt-extended.ax.

* Improved bounds for tan, with more problems.

* Corrected the Nichols plot problems (using Maple) and used scaled axioms for sqrt
  to solve some of them.

* Added parallelism to the script runmetit.pl, via the option --threads.

* Many more new problems.

MetiTarski release 1.6 2010-09-09

* Corrected a serious error in the file ln-extended.ax: the lower bounds were identical to
	the upper bounds!

* Introduced a cache for QEPCAD calls, eliminating duplicates and improving performance.

* Many more new problems.

MetiTarski release 1.5 2010-07-23

* Modifications to heuristics, e.g., now all new clauses receive arithmetic simplification.

* Efficiency improvements, in particular, direct support for rational numbers as constants.

* Faster set and map data structures, supplied by Joe Hurd.

* Corrected the log error analysis problems (using Maple). Added a few other problems.

MetiTarski release 1.4  26-05-2010

* Experimental and limited support for problems involving existential quantifiers.

* Direct upper/lower bounds for the functions tan, sinh, cosh (which previously expanded to expressions involving other functions).

* Support for the hyperbolic function tanh, with some problems.

* Reports status GaveUp rather than CounterSatisfiable when the search fails, because the algorithms are incomplete.

* The "include" directive now allows absolute path names, which begin with a "/".

* Incorporated some code from Metis 2.2 (release 20100524).

MetiTarski release 1.3  25-02-2010

* Fixed a bug that caused MetiTarski to hang by sending formulas to QEPCAD
containing the logical constants TRUE or FALSE.

* Fixed a bug that caused MetiTarski to die if the supplied clauses included arithmetic tautologies.
(Both bugs reported by Geoff Sutcliffe.)

* Nine new problems from various sources.

MetiTarski release 1.2  11-08-2009

* Support for the TPTP "include" directive. Also in the accompanying Perl scripts.

* Many new problems on analogue circuit verification, etc., from Concordia University.

* Now detects whether the supplied problem is immediately inconsistent in the theory of real closed fields (useful for problems that, after simplification, no longer contain occurrences of functions).

* New axiom file: trans.ax.

* Improved documentation.

MetiTarski release 1.1  14-01-2009

* Tuning and heuristic improvements, with significantly faster performance.

* The parser now indicates the approximate location of syntax errors. (Thanks to Joe Hurd!)

* Corrected the problem two_variable_problem_6, which needed a quantifier over Y.

MetiTarski release 1.0  02-12-2008

* Corrected serious errors in the exp upper bound definitions.

* Moved the most accurate approximations to separate files of extended bounds in order to improve performance for the harder problems, many of which do not require accuracy at all.

* Refinements to heuristics, particularly concerning case splitting on signs.

* Simplification of some problems, using a maximum of three significant digits for control and hybrid systems.

* Numerous minor adjustments to the axioms, particularly for exponentials.

* Now all problems are in first-order format!

MetiTarski release 0.9  12-09-2008

* Fixed a soundness bug concerning the normalisation of quotients.

* Corrected serious errors in the atan upper bound definitions.

* Improved bounds for the atan and log functions using continued fractions.

* Improved reasoning about rational numbers (they are smaller than Skolem constants in KBO).

* Eliminated the axiom file division.ax, combining it with general.ax.

* Added Nichols Plot problems.

* More of the problems have been converted to first-order format.

MetiTarski release 0.8  22-08-2008

* More of the problems have been converted to first-order format.

* Introduction of decimal notation: a decimal such as 1.23 abbreviates the fraction 123/100.

* Many of the problems have been converted into first-order format, with decimal notation.

* Improved bounds for the atan (arctangent) function, based on continued fractions. Many thanks to Annie Cuyt!

* Improved simplification so that quotients whose operands are complicated numerical expressions are guaranteed to be evaluated.

MetiTarski release 0.7  29-07-2008

* First public release.
