Motion P1788/M00018.01:TritsToTetrits: NO
I vote NO because I believe the issue of dependency among arguments
in a composition of functions has not been sufficiently addressed.
(I'm sorry that I didn't address this earlier, during the discussion
period -- but that fell during my vacation, and after that the motion
had dropped off my radar...)
The reasoning behind the "infimum of ranked tetrits" rule assumes
that the existential quantifications over the input arguments of
a multiple-argument function are independent.
The way the propagation rule is specified leaves out the possibility
of taking dependencies into account.
Consider the function min(x, 1/x**2) evaluated over [-2,+2].
The undefinedness of 1/x**2 at zero is covered up by the min()
operation, so that it does not matter.
A similar situation arises in case-based programming, where the
computation is deliberately arranged to avoid domain errors in
certain cases. Optimistic out-of-order execution may in fact
trigger exceptions on mispredicted paths, but the system is
supposed to defer exception reporting until paths are confirmed,
and have the capability of squashing mispredicted exceptions.
What I am missing in the Trits-to-Tetrits paper is a statement that
covers such situations, and that permits a case-based implementation
of functions such as min(x,1/x**2) that avoids reporting a domain
error.
Michel.
---Sent: 2010-07-08 18:54:46 UTC