Bernadette Bouchon-Meunier Vladik Kreinovich Fuzzy Modus Ponens as a Calculus of Logical Modifiers: Towards Zadeh's Vision of Implication Calculus. 219-227 1999 116 Inf. Sci. 2-4 db/journals/isci/isci116.html#Bouchon-MeunierK99