These proceedings consist of ten carefully refereed and selected papers which were presented at the 12th symposium of Tunisian Mathematical Society held on March 18-23, 2004 in Mahdia (Tunisia). This symposium was one of the largest international meeting on Mathematics in Tunisia. A total of 200 participants from several countries attended to the meeting. In addition to the plenary, invited and contributed talks, there was a panel discussion on future research directions and problems in various areas of mathematics.