User blog comment:Planetn9ne/NDAN fixed?/@comment-11227630-20190505022322

In subfunctions case B4, D(A) = "{n-1 #C)△" seems to be a syntax error.

In subfunctions case B1 and B2, the case description looks bad. Case B is "the section is equal to △", but the △ does not appear in the subcases, so it is hard to compare and get where the △ is in (1)○B (or (n #​C​C)○B). Certainly by the syntax definition, △ is always the ending section, but I think it better to write (1)B△ (or (n #​C​C)B△) and place them after case B3 and B4, because case B3 and B4 are more special than B1 and B2.