From Object-Orientation to Formal Methods

After Ole-Johan’s retirement at the beginning of the new millennium, some of us had thought and talked about making a “Festschrift” in his honor. When Donald Knuth took the initiative by sending us the ?rst contribution, the p- cess began to roll! In early 2002 an editing group was formed, including Kristen Nygaard, who had known Ole-Johan since their student days, and with whom he had developed the Simula language. Then we invited a number of prominent researchers familiar with Ole-Johan to sub