By using this site, you agree to our updated Privacy Policy and our Terms of Use. Manage your Cookies Settings.
435,285 Members | 2,124 Online
Bytes IT Community
+ Ask a Question
Need help? Post your question and get tips & solutions from a community of 435,285 IT Pros & Developers. It's quick & easy.

Need help: Is Quick-Union-Find the right solution to this problem (Now I don't think so and I think that topological sorting should be the way to go...?) ?

P: n/a
On Sun, 10 Apr 2005 19:46:32 GMT, ar**********@yahoo.com wrote:
The user can dynamically enter and change the rule connection between
objects. The rule is a "<" and so given two objects:
a < b simply means that b < a can't be set, also it must be a != b.
And with three objects a < b , b < c means a < c

I studied Quick Union Find algorithms a bit and if I understood them
correctly, once the user gives the input setting the rules/connection
between objects, the algorithm will give as output the result of the
solved connections between objects.

As far as I check on the array or given list of objects from user
input that it's never added anything like a = b nor b<a when a<b it's
already in the list, would it work as expected so that I know which
objects in the list are "the strongest" ones as per user given rules ?

I tried thinking about using simple logic like AND,OR,XOR of compare
results values but I couldn't find a way to ensure that the
transitivity rule could be mantained.

So, is a DAG or Quick Union Find the way to go ?

My only concern about Quick Union Find is that it constructs a graph
with a single highest level root like a tree, right ? But if I am not
wrong the user could set things in such a way that the graph would
have more than one "root" .. ?!

Someone please help me to understand what's the right thing I should
use, and the simpler one that would still let me solve the "which is
stronger" among the user given objects and user set rules.

After a bit of searching I think that I should use DAG and Topological
Sorting, right ?
Topological sorting on a DAG graph in which the user input can be
checked to avoid reflexive property to be inserted should do the
trick, no ?
Regarding transitivity property to tell the user that a given rule
can't be accepted I have to build up the topological sort list and
check on it everytime, right ?

Or, is there any simpler way to have all of this work without building
up a graph and doing topological sorting on it and so on ?

Nov 14 '05 #1
Share this Question
Share on Google+
1 Reply


P: n/a
On Tue, 12 Apr 2005 17:06:49 GMT, ar**********@yahoo.com wrote in
comp.lang.c:
On Sun, 10 Apr 2005 19:46:32 GMT, ar**********@yahoo.com wrote:
The user can dynamically enter and change the rule connection between
objects. The rule is a "<" and so given two objects:
a < b simply means that b < a can't be set, also it must be a != b.
And with three objects a < b , b < c means a < c

I studied Quick Union Find algorithms a bit and if I understood them
correctly, once the user gives the input setting the rules/connection
between objects, the algorithm will give as output the result of the
solved connections between objects.

As far as I check on the array or given list of objects from user
input that it's never added anything like a = b nor b<a when a<b it's
already in the list, would it work as expected so that I know which
objects in the list are "the strongest" ones as per user given rules ?

I tried thinking about using simple logic like AND,OR,XOR of compare
results values but I couldn't find a way to ensure that the
transitivity rule could be mantained.

So, is a DAG or Quick Union Find the way to go ?

My only concern about Quick Union Find is that it constructs a graph
with a single highest level root like a tree, right ? But if I am not
wrong the user could set things in such a way that the graph would
have more than one "root" .. ?!

Someone please help me to understand what's the right thing I should
use, and the simpler one that would still let me solve the "which is
stronger" among the user given objects and user set rules.

After a bit of searching I think that I should use DAG and Topological
Sorting, right ?
Topological sorting on a DAG graph in which the user input can be
checked to avoid reflexive property to be inserted should do the
trick, no ?
Regarding transitivity property to tell the user that a given rule
can't be accepted I have to build up the topological sort list and
check on it everytime, right ?

Or, is there any simpler way to have all of this work without building
up a graph and doing topological sorting on it and so on ?


Look back at your question, and your follow-up to your own question,
quoted above. Notice not one single mention of the C programming
language, which is our topic here. Algorithm selection is in fact
programming language independent.

If you want advice on choosing an algorithm, you should ask in a group
like news:comp.programming.

Once you have selected your algorithm, if you have difficulties
implementing it in standard C, then post your code here and explain
your problem with it, and we can help.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html
comp.lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.learn.c-c++
http://www.contrib.andrew.cmu.edu/~a...FAQ-acllc.html
Nov 14 '05 #2

This discussion thread is closed

Replies have been disabled for this discussion.