es logical sense.  Otherwise you will find youself forced back to
allowing that "(X (Y))" and "X =&gt; Y" really do mean different things,
just because somebody thinks they do.  One can distinguish, and I do
this in my own work, definitions of "referential equiv classes" (REC's),
of which LEC's are a special case, and "semiotic equiv classes" (SEC's),
but the end of logic requires a close coordination among all of these,
and I think, except for changing X, as close a congruence to identity
as we can get.  (