True. The program in the article is an expert system, not a decision tree learner. The confusion probably stems from the fact that decision tree learners are (s

True. The program in the article is an expert system, not a decision tree learner. The confusion probably stems from the fact that decision tree learners are (still?) a very popular machine learning algorithm; and because most people who are into AI and ML today don't know anything about its past. And what happens to those who don't remember the past? Ask George Santayana.