Studies on identifying parameters, values, and the interrelations of parameters of software under test. It is the fundamental activity of combinatorial testing.
Studies on generating as small test suites as possible. It is the most popular field in combinatorial testing. The many proposed techniques consist of mathematical methods, greedy methods, and search based methods.
Studies on improving the test suite by prioritization, minimization and selection techniques.
Studies on locating the concrete failure causing interactions.
Studies on measuring the effectiveness of CT and comparing CT with other testing methods.
Studies on applying, improving, and popularizing CT and its procedures in real world.
Studies that do not belong to any of the above categories.