At one step of the algorithm the 3B method will determine that there is no solution either by considering the simplification procedures provided by the end-user or by a direct evaluation of the expressions involved in the problem.

As the simplification procedures may be computer intensive you may
avoid using them within the 3B method by setting the flag
``ALIAS/Use_Simp_3B`` to 0.
Alternatively you may specify that only some of the simplification
procedures are to be used within the 3B method by using the mechanism
described in the `CatSimp` procedure (section 4.4).
You may also set ``ALIAS/Use_Simp_3B`` to 2: in that case if
some variable ranges have been improved the algorithm will check if
the whole improved set of ranges may not be a solution of the problem
by using all available simplification procedures (including the one
having a `"NO_3B"` in `CatSimp`).

As for the interval evaluation of the expressions involved in the
problem some of the procedures proposed in ALIAS-Maple may use the
derivatives of the expression to improve the interval evaluation. This
may be computer intensive and you may avoid using these derivatives
within the 3B method by setting
the variable ``ALIAS/Grad_3B``
to a list with as many elements as
number of variables. The values in this list are thresholds for the
width of the variable ranges such that the derivatives are not used if
at least one range width exceed the value.