The powerful extension of basic ealgebras considered in this subsection is logically clear but untried and computationally expensive. It does not hurt to explore it though.
Call elements a and a' of a state S indistinguishable as arguments
for a basic r-ary function f if
for all r-tuples
and
such that either
or
.
Call a, a'
indistinguishable as
arguments if they are indistinguishable as arguments for any basic function
with the exception of equality. Now we are ready to introduce the
duplicate constructor:
duplicate t as v
endduplicate