def terminate_criterion_y(verts, f_difference, x_tolerance, y_tolerance):
    """Return True if f_difference < y_tolerance, else false.

    Args:
        verts:          The verticies of a simplex
        f_difference:   The absolute difference of the last and secondlast function_value
        x_tolerance:    a real valued number or -infty
        y_tolerance:    a real valued number or -infty

    Returns:
        out: Boolean

    """
    # decide wether to stop or continue search for optimum
    if f_difference < y_tolerance:
        return True
    else:
        return False