simple solution is there. cong should stop discriminating Bengal, invest heavily there for development of roads, railways, airports, industries, educations, jobs, health, etc. Developed Bengal will not vote for CPM and problem will be solved. But I know cong will not do so bcoz cong hates Bengalis since the days of Gandhi / Nehru bcoz of their animosity towards Subhas Bose. And bjp will only try to forcibly impose Hindi & north indian culture killing Bengali culture and tradition which will not be accepted by general Bengalis. Unless Indians change their attitude of hatred towards Bengalis and respects them as equally important Indians things will not improve.
