Pyomo

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- Made the imports of pyomo.opt services more robust to the failure of
individual services.

- Minor performance improvement

- Fixing import error when ordereddict is not available.

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- Bug fix for Python 2.7 installation.

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The following are highlights of this release:

- Solvers
* Interfaces for OpenOpt solvers
* Many solver interface improvements
* A solver checker to validate solver interfaces
* Improved support for SOS constraints (cplex, gurobi)
* PH supports nonlinear models
* PH-specific solver servers

- Modeling
* Changes in rule semantics to limit rule return values
* Changes in the expected order of rule arguments
* Constant sums or products can now be used as constraint bounds
* Added full support for the !ConstraintList modeling component.

- Usability enhancements
* New 'pyomo' command has subcommands that consolidate Pyomo scripting
* Added support to connect to databases with ODBC
* Added comprehensive support for set expressions
* Comprehensive rework of blocks and connectors for modular modeling
* Made JSON the default results format

- Other
* Efficiency improvements in model generation, memory, runtime, etc.
* Preliminary support for black-box applications
* Deprecated modeling syntax in Pyomo 3.0 is no longer legal


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- Solvers
* More sophisticated logic for solver factory to find ASL and OS solvers
* Various solver interface improvements
* New Solver results object for efficient representation of variable values
* New support for asynchronous progressive hedging

- Modeling
* Changes in rule semantics to limit rule return values
* Changes in the expected order of rule arguments
* Constant sums or products can now be used as constraint bounds
* Added full support for the ConstraintList modeling component.

- Usability enhancements
* More explicit output from runph and runef commands
* Added support in runef to write the extensive form in NL format
* Add controls for garbage collection in PH

- Other
* Efficiency improvements in generation of NL and LP files.
* Significant efficiency improvements in parsing of Pyomo Data Files.
* More robust MS Windows installer (does not use virtual python environment)

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- Performance improvements in Pyomo

- Bug fix when updating a results object that contains suffix data.

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- Solvers
* MIP solver interface updates to use appropriate objective names
* Added support for suffixes in GUROBI solver interface
* Improved diagnostic analysis of PH solver for the extensive form

- Usability enhancements
* Improved robustness of pyomo_install
* Fixed Pyomo installation problem when using easy_install
* Added a script to launch the PyomoAge GUI.
* LP files now are written with the true objective name
* Rework of pyomo command line to create a concise output
* Many efficiency improvements during model generation!
* Many improvements to diagnostic output and error handling
* Expressions like "model.p > 1" can now be used within generation rules

- Modeling
* Added support for generalized disjunctive programs (in pyomo.gdp)
* Constraints can now be specified in "compound" form: lb <= expr <= ub
* Significant robustness enhancements for model expressions
* Improved error handling for constraint generation

- Other
* Python 2.5 is deprecated due to performance issues
* Python versions 2.6 and 2.7 are supported
* New MS Windows installer is now available

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