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 first contribution, the process
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 submit contributions for a book honoring
Ole-Johan on the occasion of his 70th birthday. Invitees included several
members of the IFIP 2.3 working group, a forum that Ole-Johan treasured and
enjoyed participating in throughout his career. In spite of the short deadline, the
response to the invitations was overwhelmingly positive