It depends on your point of interest. It also depend on your approach. If you are interested in a cognitive approach try to find something related to the prototype theory (E. Rosch).

If you are interested in  the semantic approach of actants ( the Case theory may also be useful in one of the appraoches -localistic or not- or tha theory developped by Frawley oe any other linguist).

Try to be more explicit, I do not quite follow you: what exacly do you mean by "problems" : something that can hinder the study ?  problems in the sense of "matters"?

If you can be more explicit, perhaps you will find an answer to your question.

Liliana Alic

I am doing my research in question answering system and i wish to work from the semantic approach.. what are the areas can i work from.. 

You can query semantic data available in RDF form with the help of SPARQL to get more accurate and related result. For this you need to understand semantic behind user query and data to be in semantically related form.

Hi Aarthi, maybe this is something you could use (agree that your question is not clear)

https://igw.tuwien.ac.at/igw/Menschen/hofkirchner/papers/InfoScience/Unified_Infotheory/namur.html

http://www.mdpi.com/2078-2489/3/2/204/htm

or

http://anthropology.berkeley.edu/sites/default/files/WhatIsMissingFromInfo.pdf

You can do as Aniruddh suggests or if you prefer to work at the text level you may use data on semantic similarity and semantic associations between words both to extend the set of passages considered for finding the answer and to judge the correctness of candidate answers.