On Tue, Aug 26, 2014 at 10:03 PM, Chris Smith <[email protected]> wrote:
>
>> Or I don't understand your problem [about the problem with calling for
>> arg in the new assumptions handler]
>>
>
> The problem is that arg is written using old assumptions, so unless you
> rewrite arg to use the new assumptions and pass assumptions along to it,
> you won't get the benefit of its computations. Here's a trivial example
> using foo instead of arg but hopefully the point comes across:
>
> def foo(e):
> if e.is_positive: return True
> return False
>
> Say that in a NEW handler you want to try
>
> ...
> if foo(e): return 1
> else: return 2
> ...
>
> You will always get 2 if e is a symbol because when you call, say,
>
> ask(Q.Bar(x), Q.positive(x))
>
> x has no direct assumption so False will be returned from foo and thus 2
> will result from the ask. So unless we either 1) assign assumptions to
> symbols (but that will not be sufficient to handle things like Q.positive(x
> + 2) or 2) start passing assumptions to all functions which have a
> dependence on assumptions (so something like def foo(e) -> def foo(e,
> assumptions={})) I don't know how we are going to get the
> old-assumptions-API-based functions to start working with the new
> assumptions. What am I missing? How will foo above need to be modified so
> it works?
>
This is asking for the reverse of what I am suggesting. I am suggesting
making the new assumptions recognize assumptions made in the old
assumptions. You want the old assumptions to recognize assumptions made in
the new assumptions.
I tried doing it both ways, and it failed. It's too much work. I think just
doing it in one direction is better, as then it only affects calls to
ask(). We could even limit it further so that ask() only looks at the old
assumptions on symbols. I suspect this change would lead to no test
failures.
Aaron Meurer
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