New in Version 1.8.1 (1 August 2014)

• Look and feel improvements.
• Minor performance enhancements, especially for the QBF preprocessor.
• Proof tree drawing improved.

Version 1.8 (1 March 2013)

• User registration is no longer required.
• New feature: qpro file import.
• New feature: experimental support for GUI-less mode (e.g. without X server).
  Usage: java -Djava.awt.headless=true -jar proverbox.jar cmd1 cmd2 ...
  where cmd1 cmd2 ... are ProverBox commands as entered on the command prompt.
  Commands must be wrapped in quotes if they contain spaces.
  Example: java -Djava.awt.headless=true -jar proverbox.jar 'qdimacspreprocess "/tmp/file.qdimacs"'
  which runs the QBF preprocessor on the file /tmp/file.qdimacs and is equivalent to
  entering qdimacspreprocess "/tmp/file.qdimacs" on the prompt of the ProverBox GUI.
• Once again, the QBF preprocessor has been improved.
• The plugin API now includes a library for combinational Boolean circuits.
• The complete plugin API is now using generics.
• Other minor improvements and bugfixes.
• Notice: Java 7 or higher is now required.

Version 1.7 (14 August 2010)

• Once again, the QBF preprocessor has been improved.
• Changes to the plugin API.

Version 1.6 (27 March 2010)

• Significantly improved QBF preprocessor.
• Significantly improved resolution for predicate logic.

Version 1.5.5 (28 January 2010)

• Bugfix for problems with tautologies and free variables in the (Q)DIMACS file import.

Version 1.5.4 (22 September 2009)

• Improved QBF preprocessor.
• New feature: display statistics about QCNF* formulas.
• Bugfix: incorrect QBF preprocessing statistics.
• Bugfix: incorrect handling of files passed on command line.

Version 1.5.3 (21 November 2007)

• New feature: ProverBox is now fully scriptable through the system command line.
• Improved statistics output for QBF preprocessor.

Version 1.5.2 (20 September 2007)

• Improved random formula generator for QHORN.
• Bugfix for QBF preprocessor.

Version 1.5.1 (12 June 2007)

• Improved QBF preprocessor.

Version 1.5 (23 May 2007)

• New feature: QBF preprocessor.
• New feature: universal expansion for QBF*.
• New feature: finding Horn renamings in propositional logic and QBF*.
• Enhancement: additional options for customizing ProverBox.
• Enhancement: ability to suppress large output.
• Bugfix: incorrect frame dimensions at startup.

Version 1.4 (11 December 2006)

• DIMACS and QDIMACS import and export.
• DavisPutnam module: can now prove and solve.
• Internal improvements in handling large formulas.
• Lots of minor enhancements and bugfixes.

Version 1.3.2 (20 January 2006)

• Bugfixes and performance improvements.

Version 1.3.1 (13 December 2005)

• Performance improvements.

Version 1.3 (05 December 2005)

• Random formula generator for QBF*.
• Performance improvements.
• Minor enhancements and bugfixes.

Version 1.2 (01 December 2004)

• New specification language: QBF*.

Version 1.1 (17 June 2004)

• It is now possible to use propositional expressions in predicate logic.
• New license management.
• Preferences dialog added.
• Resolution module: significant performance improvements.
• Minor enhancements and bugfixes.

Version 1.0.6 (18 February 2004)

• Improved Skolemization algorithm.

Version 1.0.5 (15 December 2003)

• Command prompt: tab key allows reusing previous result.
• Minor enhancements and bugfixes.

Version 1.0 (03 September 2003)

• Significantly improved resolution module.
• New option to generate a complete CNF for a propositional formula.
• Davis-Putnam module: a counterexample is provided if a theorem is not provable.
• Improved error handling in command prompt and editor.
• Other minor enhancements and bugfixes.

Version 0.9 (18 August 2003)

• Added proof tree output feature to I/O manager.
• Improved output for resolution module.
• Multithreading: commands can now be executed as independent threads.
• Added Undo / Redo feature to editor.
• Lots of minor enhancements and bugfixes.

Version 0.8 (05 August 2003)

• New formula manager hierarchy.
• Library routines for predicate logic.
• New module: Resolution.
• Support for commands with flags.
• Added "CLS" command, allowing to tidy up the screen.
• Improved help system.
• Automatic declarations now supported by user interface.

Version 0.7 (22 July 2002)

• Specification files now use XML.
• Added parser.
• Implemented language manager.
• Modular architecture for formula and symbol managers.
• New specification language: propositional logic.
• View menu added.
• Project name changed to ProverBox.
• Improved command prompt with support for nested commands.
• Added commands for axiom and theorem handling.
• Improved help system.
• Added predefined types "ANY" and "BOOL".
• Added auto declare.
• Improved plugin API.
• Comfortable user interface for selecting current language and module.
• Added support for formulas in CNF clause-set representation.
• New commands for transforming formulas into propositional normal forms.
• New command: truth tables for propositional formulas.
• Support for embedding components in the output.
• Included sample module: DavisPutnam.

Version 0.6.1 (21 December 2001)

• Bugfixes.

Version 0.6 (19 December 2001)

• Editor added.
• User Settings implemented.
• Command prompt: added command history.
• Working menu bar.
• Optimized resizing behavior.

Version 0.5 (17 July 2001)

• New syntax for declarations.
• Improved handling for the equivalence operator.

Version 0.4 (27 June 2001)

• Formula manager added.
• Command prompt: error reporting improved.

Version 0.3 (24 June 2001)

• Further work on help system.
• Better error reporting when using the command prompt.
• About and version commands added.
• Plugin interface revised.
• Symbol manager now produces sorted output.
• Added simple I/O commands.

Version 0.2 (13 June 2001)

• Help system introduced.
• Symbol manager completed.
• Resource management improved.
• Bugfixes.

Version 0.1 (18 May 2001)

• Symbol manager introduced.