In Memoriam: John G. Gaschnig

JOHN GASCHNIC, used to come into my office quite regularly for conversations that helped calibrate my mental compass. John had definite opinions about many subjects-about how N research ought, to be pursued, about high standards of achievement, about the need for first-rate equipment, about important research topics, about personnel mattersin short, about all the sorts of things that concern me. John was persuasive and not easily deflected. Well, actually, he couldn’t be deflected at all! Usually, I agreed with John and welcomed the added strength that he gave me. Sometimes, though, I might try to explain that something he was advocating wasn’t “realistic.” That line didn’t work at all-he could cite many examples of people who overcame constraints of pract,ical realism or “politics” and went on to achieve something truly important. A piece of John remains with me to help fight the good fights. When we disagreed, <John’s attitude about my counter-arguments was that they were merely bothersome hurdles that he would eventually overcome. I wish he were still here to overcome them. John was best known lately for his work on expert systems, notably the PROSPECTOR geological exploration system developed in our laboratory. His work on PROSPECTOR brought him justifiable world-wide fame-among AI people as well as among economic geologists. John thought it FXtremely important that AI mature as a rigorous science. His dissertation at Carnegie-Mellon University on search and intelligent backtracking is a model of how one ought, to do first class experimental work in AI. He was enthusiastic about recent theoretical progress on heuristic search-seeing in this work evidence of the solid underpinnings that he thought were missing in much of AI.