Rough set theory proposes a new mathematical approach to imperfect. knowledge, i.e. to vagueness (or imprecision). In this approach, vagueness is expressed by a boundary region of a set.

- Pakistan Mathematical SocietyThe PakMS was registered on 16th November 2001. The Society had to apply again for registration under the ACT XXI of 1860 to meet the requirement of the Pakistan Science Foundation for registration of the society with it. It was finally registered under this Act on 17th February 2003.
- American Mathematical SocietyThe interests of mathematical research, scholarship and education, serving the national and international community through publications, meetings, advocacy and other programs.
- European Mathematical SocietyThe European Mathematical Society is a learned society representing mathematicians throughout Europe. It promotes the development of all aspects of mathematics in Europe, in particular mathematical research, relations of mathematics to society, relations to European institutions, and mathematical education.
- The London Mathematical Societyhe provision of grants to support mathematics, especially conferences and joint research activities linking groups at different Universities. It is particularly concerned to provide help for young mathematicians (including research students). It also has schemes to support educational outreach activities and assistance to those with home commitments who wish to attend conferences, etc.

- Canadian Mathematical SocietyThe Canadian Mathematical Society (CMS) was originally conceived in June 1945 as the Canadian Mathematical Congress. The founding members hoped that "this congress [would] be the beginning of important mathematical development in Canada". Seeking to end confusion with the quadrennial mathematical congresses, a name change was considered for many years. Finally, upon its incorporation as a non-profit, charitable organization in 1978, a new name was adopted - the Canadian Mathematical Society.
- The Mathematical Programming SocietyThe Mathematical Programming Society is an international organization dedicated to the promotion and the maintenance of high professional standards in the subject of mathematical programming. It is incorporated as a non-profit tax-exempt scientific organization in the United States. It publishes the journals Mathematical Programming A and B, consisting of technical articles on all aspects of the subject; the MPS/SIAM Series on Optimization, comprising monographs and texts on particular optimization topics; and the newsletter Optima
- Foundations of Computational MathematicsThe computer has profoundly changed the relationship between mathematics and computation. Besides its invaluable role in numeric, symbolic, and experimental applications, computation is an important object of mathematical study in its own right and a fundamental theoretical tool. It is a source of new and exciting problems for mathematics