(self, cls)
Handle the addition of a new clause for the VSIDS heuristic.

        Examples
        ========

        >>> from sympy.logic.algorithms.dpll2 import SATSolver
        >>> l = SATSolver([set([2, -3]), set([1]), set([3, -3]), set([2, -2]),
        ... set([3, -2])], set([1, 2, 3]), set([]))

        >>> l.num_learned_clauses
        0
        >>> l.lit_scores
        {-3: -2.0, -2: -2.0, -1: 0.0, 1: 0.0, 2: -2.0, 3: -2.0}

        >>> l._vsids_clause_added(set([2, -3]))

        >>> l.num_learned_clauses
        1
        >>> l.lit_scores
        {-3: -1.0, -2: -2.0, -1: 0.0, 1: 0.0, 2: -1.0, 3: -2.0}
Handle the addition of a new clause for the VSIDS heuristic.
Handle the addition of a new clause for the VSIDS heuristic .
def _vsids_clause_added(self, cls):
        """Handle the addition of a new clause for the VSIDS heuristic.

        Examples
        ========

        >>> from sympy.logic.algorithms.dpll2 import SATSolver
        >>> l = SATSolver([set([2, -3]), set([1]), set([3, -3]), set([2, -2]),
        ... set([3, -2])], set([1, 2, 3]), set([]))

        >>> l.num_learned_clauses
        0
        >>> l.lit_scores
        {-3: -2.0, -2: -2.0, -1: 0.0, 1: 0.0, 2: -2.0, 3: -2.0}

        >>> l._vsids_clause_added(set([2, -3]))

        >>> l.num_learned_clauses
        1
        >>> l.lit_scores
        {-3: -1.0, -2: -2.0, -1: 0.0, 1: 0.0, 2: -1.0, 3: -2.0}
        """
        self.num_learned_clauses += 1
        for lit in cls:
            self.lit_scores[lit] += 1
def _vsids_clause_added ( self , cls ) : self . num_learned_clauses += 1 for lit in cls : self . lit_scores [ lit ] += 1