Re: Subsets and adjacent values

I'm playing with Data::PowerSet. It creates all subsets of a list of elements.

I personally believe that before proceeding you should clarify your terms, especially those I highligheted above, since Mathematics is based upon precise definitions. You start talking about sets, and subsets, then mix them arbitrarily with lists. But sets and lists are different mathematical objects, albeit relatively similar ones. For sets, you cannot speak of "adjacency" while for lists you can.

Now, unless I'm grossly mistaken, it seems to me that your problem may be translated into an equivalent but simpler one, namely that of finding all of the substrings of a given string, perhaps with a constraint on their lenght, as per your example. HTH.

--
If you can't understand the incipit, then please check the IPB Campaign.

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Re^2: Subsets and adjacent values by pc88mxer (Vicar) on May 30, 2008 at 15:44 UTC
There is a little confusion of terms going on here. Mathematically a set is an un-ordered collection. However, the `powerset()` routine in `Data::PowerSet` returns arrays which are ordered. What `powerset()` is really doing is producing all the sub-sequences (with gaps between elements allowed) of the input sequence. If your input sequence contains distinct elements, then you can think of it as being a set and think of all of the generated sub-sequences as subsets. That is, there is a correspondence between a sequence of distinct elements and the set consisting of those elements. So, the `powerset()` routine can be used to produce either 1) all the sub-sequences of a given sequence or 2) all the subsets of a given set.	[reply] [d/l] [select]
Re^3: Subsets and adjacent values by blazar (Canon) on May 30, 2008 at 18:55 UTC
I personally believe all this is evident and obvious, but... I can't understand why you're telling me! I knew. Still stands the point I tried to make to the OP: namely, that he should carefully choose the frameset for the problem. He reasoned in terms of sets: that these are "implemented" (please bear with me being slightly sloppy wrt terminology) with lists in the referenced module was considered a side effect to be used afterwards, which suggested him an overkill of an algorithm, while if he had resoned in terms of lists in the first place, he would have probably chosen a saner one to start with. `--` If you can't understand the incipit, then please check the IPB Campaign.	[reply] [d/l]
Re^4: Subsets and adjacent values by pc88mxer (Vicar) on May 31, 2008 at 17:48 UTC
Sorry, by placing my reply under your node I didn't mean to imply that you were confused. It just seemed like a good opportunity to bring up the fact that `powerset()` can be used for either sequences or sets.	[reply] [d/l]
Re^2: Subsets and adjacent values by andreas1234567 (Vicar) on Jun 02, 2008 at 09:16 UTC
You start talking about sets, and subsets, then mix them arbitrarily with lists. But sets and lists are different mathematical objects, albeit relatively similar ones. Good point. As the OP I humbly apologize and take full responsibility for the confusion that followed the initial post. -- No matter how great and destructive your problems may seem now, remember, you've probably only seen the tip of them. [1]	[reply]