  In this article, we illustrate how the concept of slope limiter can be
interpreted graphically, i.e., how the slope of reconstructed piecewise linear
function is limited by four bounding lines that connect cell-averaged data and
its neighboring cell-averaged data. It is then conjectured that the same
graphical rule can be generalized from uniform mesh to non-uniform mesh, such
that the high-resolution total variance diminishing (TVD) region of slope
limiter for non-uniform meshes can be obtained.
