The Tuner Method (.xtm) File

The tuner method file is in a straightforward plain text format. For example, when the two controls MAXTIME and THREADS are set by the user on the current problem and then XPRStunerwritemethod is called, the generated xtm file will look similar to the following:

FIXED-CONTROLS
  MAXTIME              = 100
  THREADS              = 1
TUNABLE-CONTROLS
  SBEFFORT             = 0.25, 4
  HEURSEARCHEFFORT     = 0.5, 2
  CUTFACTOR            = 0.5, 1, 5
  SCALING              = 0
  PRESOLVE             = 0
  VARSELECTION         = 2, 7
  CUTFREQ              = 2
  SYMMETRY             = 0, 1, 2
  COVERCUTS            = 0, 2
  GOMCUTS              = 0, 2, 10
  TREECOVERCUTS        = 0
  TREEGOMCUTS          = 0
  HEURSTRATEGY         = 0
  SBESTIMATE           = 1, 2, 3, 4, 5, 6
  HEURSEARCHROOTCUTFREQ= 2, 5
  HEURSEARCHROOTSELECT = 0, 3, 5
  HEURSEARCHTREESELECT = 0, 3, 5
  ROOTPRESOLVE         = 1
  PREPROBING           = 3
  BRANCHDISJ           = 0

The tuner method file consists of a section of fixed controls and a section of tunable controls.

The fixed controls

The fixed controls section starts with FIXED-CONTROLS, followed by control setting lines in assignment form. Each control in this section can only be assigned to one value. If the same control appears several times in this section, its first appearance will be used.

When writting out the tuner method file, all the controls set for the current problem will be included in the fixed control section. When reading in the tuner method file using XPRStunerreadmethod, these controls won't be applied to the current problem immediately, they will only be applied to the worker problem used in the tuner.

This section can be empty.

The tunable controls

The tunable controls section starts with TUNABLE-CONTROLS, followed by control setting lines in assignment form. Each control in this section can be assigned to one value, or multiple values seperated by commas. A control may appear multiple times in this section.

When reading in a tuner method file and writing it out again, the tunable controls may appear in a different order. If there is a control appearing multiple times in the original tuner method file, when written out, it will be combined into a single line with multiple values.

For bit vector controls, such as PRESOLVEOPS, SCALING, or HEURSEARCHROOTSELECT, it is possible to either specify concrete assignments to the control or to specify individual bits that should be used for tuning. In the latter case, one has to use a colon instead of an equals sign. For example, "SCALING = 24, 675" will tune using the two given concrete values 24 and 675, while "SCALING : 3, 4, 9" will individually toggle bits 3, 4, and 9 of the default value for SCALING and potentially also try combinations of those later during tuning.

This section can be empty. When both the fixed and the tunable secitons are empty, the tuner will then use a pre-defined factory tuner method.