code: public List<Formula> newLowerBound(int rhs) {
      this.result.reset();
      this.computeLBConstraint(this.result, rhs);
      return this.result.result();
    }
docs: Tightens the lower bound of an at-least-k constraint and returns the resulting formula.
  @param rhs the new upperBound
  @return the incremental encoding of the new lower bound