High Quality Content by WIKIPEDIA articles! Dcas is a dynamic computer algebra system featuring the idea of using identities as rules for manipulation of algebra. Robert Fenichel developed a system called FAMOUS in the 1970s using the LISP programming language pursuing the same aim. A modern system DCAS has been implemented by Martin Johansen called DCAS Ether. The system works by selecting a class of identities based on the form of the input expression. Here are two examples of identity collections, one for basic algebra, the other for Boolean algebra.