[comp.lang.prolog] WAM question

axaris@acsu.buffalo.edu (vassilios e axaris) (09/27/90)

Hello,

I need some clarification on the following:
Using a unified stack model for wam (ie. choice points and environments on same
stack) I can understand why the current environment may not be at the top of the
stack, by being burried under at least one choice point.
However, using the split stack model (ie. environments and ch. points reside on
different stacks) how can the current environment not be at the top of the 
environment stack? Which are the cases that give rise to such situation?
I' d appreciate any comments. Thanks in advance,

Vassilios E. Axaris
SUNY@Buffalo Computer Engineering.