We discuss the use of weakening and strengthening steps in calculational proofs. We present a metatheorem concerning monotonicity of positions in a formula that should have a more...
This review paper will report on some recent discoveries in the area of Formal Languages, chie y by F. Otto, G. Buntrock and G. Niemann. These discoveries have pointed out certain ...
We define simple-regular expressions and languages. Simple-regular languages provide a necessary condition for a language to be outfix-free. We design algorithms that compute si...