kaolin-so3h as a new solid acid is prepared via reaction of kaolin and chlorosulfonic acid. this natural based catalyst is very inexpensive and easy available. imidazoles are an important class of heterocycles being the core fragment of different natural products and biological systems such as anti-allergic, anti-inflammatory, analgesic, antifungal, antimycotic, antibiotic, antiulcerative, anti...

In this paper, stable sets for simple games with ordinal preferences are studied in the case where the number of alternatives is finite. It is shown that the condition for the existence of a nonempty core for any possible combination of players' preferences is also a necessary and sufficient condition for the existence of a unique stable set. Moreover, a necessary and sufficient condition that ...