============================================================
  fzn_izplus
     -- iZ based solver for MiniZinc Challenge 2013 --

  Copyright (C) 2013 NTT DATA SEKISUI SYSTEMS CORPORATION.
============================================================

* What is fzn_izplus

  fzn_izplus is a FlatZinc solver using iZ-C constraint programming
library which is developed by NTT DATA SEKISUI SYSTEMS CORPORATION.

iZ-C provides :
  * many built-in constraints
  * constraint propagation mechanism
  * simple search strategy

And in fzn_izplus, following algorithms are 'plus'ed.

  * Randomized restarting in search
    For fast random number generation, Xorshift128 algorithm is used.
       http://www.jstatsoft.org/v08/i14/paper

  * Local search for optimization
      In real world problem, sometimes finding 'good' solution using
    short time is more important than finding 'best' solution using
    long time. And it is known empirically that 'good' solutions are
    similar to each other, then local search can be a good strategy.
    
      For optimization problem, fzn_izplus tries to find first solution
    using constraint propagation. After one solution was found, it
    searches similar solutions better than first one.
      To avoid local minimum/maximum problem, multiple solutions are
    preserved for next search start point.

  * Variable reordering
      Failures occured in search are recorded and variable selection
     order is changed using that information.
     In combination with restarting, solver can learn problem structure.

* Author

  Toshimitsu FUJIWARA <fujiwarat@ndis.jp>
    developer at NTT DATA SEKISUI SYSTEMS CORPORATION


* Acknowledgement

  FlatZinc parser in fzn_izplus is based on 'FlatZinc parser skeleton'
written by Guido Tack. 

    http://www.gecode.org/flatzinc.html/

  Please refer to header files in flatzinc_skeleton-1.3.zip
About its copyright and license. (It's contained in this archive.)
  Special thanks to Guido Tack and Gecode team.


  iZ-C is a constraint programming library developed by
NTT DATA SEKISUI SYSTEMS CORPORATION.

   http://products.ndis.jp/iz/download.html

(Sorry, above web page is NOT written in English.)