public static Dictionary <ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode> ComputeBottomUpMapping(ISymbolicExpressionTreeNode n1, ISymbolicExpressionTreeNode n2, bool strict = false)
        {
            var calculator = new SymbolicExpressionTreeBottomUpSimilarityCalculator {
                MatchConstantValues = strict, MatchVariableWeights = strict
            };

            return(calculator.ComputeBottomUpMapping(n1, n2));
        }