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problem.addcbcutround

Purpose
Declares a callback function that is called when the Optimizer could separate cutting planes during the branch and bound search. The callback allows a user to modify when the Optimizer should separate cutting planes. It also allows a user to tighten the local node problem. This callback function will be called in addition to any callbacks already added by XPRSaddcbcutmgr.
Synopsis

problem.addcbcutround(callback, data, priority)

action = callback(my_prob, my_object, ifxpresscuts)
Arguments
callback 
The callback function which takes three arguments, cbprob, cbdata and ifxpresscuts and has an integer return value. This function is called before each potential round of cut separation in the branch and bound search.
my_prob 
The problem passed to the callback function, callback.
my_object 
The user-defined object passed as object when setting up the callback with addcbcutround.
ifxpresscuts 
An integer set to 1 if the Optimizer will apply a round of cuts after this callback. 0 otherwise.
action 
An integer return value that specifies the action the Optimizer should take:
-1 
Continue unchanged. The default action.
0 
No further rounds of cuts should be applied on this node.
1 
The Optimizer should apply one more round of cutting, regardless of the value of ifxpresscuts
2 
The Optimizer should process any changes applied during this callback and fire the callback again, but skip any Optimizer cutting.
data 
A user-defined object to be passed to the callback function, callback.
priority 
An integer that determines the order in which callbacks of this type will be invoked. The callback added with a higher priority will be called before a callback with a lower priority. Set to 0 if not required.
Further information
1. The current node problem can be modified in this callback, including adding cuts and changing bounds. If the problem is changed, the node LP relaxation will be resolved and the callback fired again.
2. It is possible to add new solutions using XPRSaddmipsol. These will be checked immediately after the callback, but adding solutions will not automatically trigger another firing of this callback.
3. If cutting planes are added to the problem or removed from the problem, or bounds tightened, a reoptimization of the node LP relaxation will automatically be triggered. The callback will only be fired again after the reoptimization if a non-zero value is returned in p_action.
Related topics
problem.removecbcutround

Parent Topic Methods of the class problem

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