All arrays can be adjustable?

[David C. Plummer <DCP@QUABBIN.SCRC.Symbolics.COM>]

Well, I guess I blew it.  (I had it right when I first wrote it and then
made the mistake of thinking too much and conversed everything.)  The
idea still stands: figure out formal relationships and draw conclusions
from them.  What I meant, in IF-THEN language, was
  Statement:
	IF  not adjustable, and
	    no fill-pointer, and
	    not displaced
	THEN
	    simple
  Contrapositive (for those that believe in it):
	IF not simple
	THEN
	   adjustable, or
	   fill-pointer, or
	   displaced

I agree with whoever (Moon?) said that simple is largely a semantic
concept that allows implementations to get leverage if they can.