[Haskell-cafe] Wrong Answer Computing Graph Dominators

Dan Weston westondan at imageworks.com
Thu Apr 17 19:11:33 EDT 2008


 > I'm not sure I agree this is the common definition of dominators

Is one undefeated if one has never fought?

 > I should only ask for the dominators of nodes which I know are
 > reachable from the source node, right?

Yes.

Denis Bueno wrote:
> On Thu, Apr 17, 2008 at 5:52 PM, Dan Weston <westondan at imageworks.com> wrote:
>> Your reasoning differs from the usual understanding of a null product (1 or
>> True), as compared to a null sum (0 or False):
>>
>>
>>  > the list of nodes for which
>>  > *any path* from source to x must touch, i.e., the list of dominators
>>  > of x.
>>
>>  Here, "any path" means all paths, a logical conjunction:
> 
> I'm not sure I agree this is the common definition of dominators, but
> supposing it is: the upshot is that to get what I expect, I should
> only ask for the dominators of nodes which I know are reachable from
> the source node, right?
> 



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