cut is used to define user-specified cuts for the global solver BMIBNB.
F = cut(X,'tag')
The result from the command is nothing but a standard constraint.
P = sdpvar(2,2); F = cut((P-eye(2))*(P-eye(2))>=0); +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | ID| Constraint| Type| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | #1| Numeric value| Matrix inequality (quadratic) 2x2| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
The only difference is that this constraint will not be used in the upper bound problem in the branch & bound procedure. The constraint will thus only be used to improve the lower bound relaxations.