Release notes for GCG 1.0

GCG 1.0

features

• include variable deletion code
• add a block diagonal detector (cons_connected)
• add a new default constraint based decomposition format with reader (dec)
• added new heuristics gcgrins and xprins
• decompositions from multiple detectors are compared in cons_decomp.h
• added block diagonal detection code, GCG solves these more intelligently
• added detection of standard problems to block detection code
• add additional statistics
• structure information can now contain presolving information
• GCG works with SCIP version 3.0

plugins

• reworked decdecomp structure handling
• merge recent SCIP heuristic changes to their GCG counterparts

bug fixes

• try to deal with the time limit of the master by looping until the original instance hits the time limit
• try to avoid infeasible problems if the timelimit is hit during farkas pricing
• fix bugs related to copying master solutions to the original problem
• fix bugs where solutions are not correctly freed
• fix bug: heuristics that use SCIPcopy really create a working copy
• fix propagation bugs
• fix issues with empty problems and problems solved in the root node
• rewrite relaxcolsel heuristic
• moved probing methods to relax_gcg.c and fixed heuristics to use them
• fix a vardata creation bug
• copy cuts in LNS heuristics correctly
• fixed bugs related to presolving
• fixed bugs related to linking variables
• fixed bugs in Ryan-Foster branching
• fix some memory issues

code cleanup

• updated the documentation
• cleaned up code (whitespace and code style changes)
• removed all vardata accesses from all files
• removed a lot of old code
• remove dead code and give the code some love
• refactored some parts to remove large methods
• cleaned up detector interface
• make sure code is clean with all our compilers and code checking tools

performance

• adjusted default parameters
• improve memory handling by switching to buffer memory in appropriate cases and away from buffer in others

interface

• make githash look nicer
• nicer decomposition output

Makefile and scripts

• add lint directory for static code analysis
• add SCIP target to makefile
• fix scripts for RWTH Aachens high performing cluster
• add possibility to create SCIP link automatically
• add small testset to enable small functionality tests
• add some modes to test script in order to create and collect decompositions
• fix clean rule to a safer version