Hi Soumen,

I'm sorry I don't have time to look at your problem properly but you may
be interested to know that the subject of processing tree-structured
dependencies (which is what a DAG is, if I understand it correctly) came
up recently  - a problem is described at

	http://www.biglist.com/lists/xsl-list/archives/200105/msg00390.html

and solutions are at

	http://www.biglist.com/lists/xsl-list/archives/200105/msg00425.html

and 

	http://www.biglist.com/lists/xsl-list/archives/200105/msg00455.html

Hope this helps -

Francis.

 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list