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Critical comments on HEURS paper
I already mentioned the claring lack of a solid example, with which the
reader can begin to understand these axes.  This might be a tricky task,
as I'm not convinced your diagram will work, for the following reasons:
[I'm not saying it wouldn't; only that you haven't provided a proof of the
following essential points:]

1) Yes, you did justify that for most tasks, any given heuristic will have
a small negative value -- corresponding to the time to evaluate the IF clause.
[I would claim that value is not as negative as one might think, as the fact that
H#37 knows it doesn't apply to Task#44 is itself useful information, which a
meta-level observer might use to great advantage.]

2) Yes, I accept the premise that if the IF part of a heuristic is mis-tuned
then the user will lose by applying that rule -- and so the utility will be
negative, and perhaps fairly large.

3) I do believe that SIMILIAR heuristics will apply to similiar tasks. It
requires a small leap of faith to accept the premise that one could apply
the SAME rule-of-thumb to more than one task, and in more than one domain.
This essential presumption could be established by claiming (as we have)
that each rule is really a fairly general entity, which may be passed 
a set of parameters which fits the general
principle to the specific case. (See UNITS Spec relation.)
Notice an important side-effect springs from the idea of "passing the
domain specifics" as an argument:
This means it is meaningful to discuss a Task axis, as done in the paper,
and helps define it as well; or at least provide
a language in which such a definition can be stated.

4) There are a lot of questionable assumptions you made about the graph
of task as function of utility. (This is one of the problems will applying the 
"When in doubt,  draw a diagram" heuristics to as fuzzy a field as heuristics...)
a) Even granting that there is a well defined domain of tasks, it's not clear
that f#23, which maps the utility of H#23 as a function of task, will be
continuous.
b) Why do you assume that all n*m graphs of all N heuristics will have
a single hump? I'll grant that for H#19, one
can twiddle the axes of the (i,j) graph to move all the humps into one
contiguous region; but this does NOT imply that the other n-1 graphs, using
this same scale for the abscissa, will also have a single peak.
An this says nothing about the other N-1 hueristics - in particular of the shape
of each of their n*m graphs, using these coordinates.

------
One single well-described example will help the reader thru points 1-3 above.
Two such examples are a necessary first stab at defining the space, and
proving (or possibly disproving) your empirical-sounding claims about
the shape and niceness of that space.
	Russ