Non-determinism in Cs High-school Curricula

1 Michal Armoni, The Open University of Israel and Tel-Aviv University, 16 Klausner St., Ramat -Aviv, P.O. Box 39328, Tel-Aviv, 61392, Israel, [email protected] 2 Judith Gal-Ezer, The Open University of Israel, 16 Klausner St., Ramat-Aviv, P.O. Box 39328, Tel-Aviv, 61392, Israel, [email protected] Abstract One of the units in the relatively new high school CS curriculum which is being implemented in Israel is a theoretical unit on computational models. It includes deterministic and non-deterministic finite automata, regular and non-regular languages, closure properties of regular languages, pushdown automata, closure properties of context free languages, Turing machines, the Church-Turing thesis and the halting problem. This paper focuses on part of a study we conducted on the unit, dealing with the topic of non-determinism of finite automata. One of the aspects dealt with was how students perceived non-determinism. 339 students were given a relatively complicated regular language, and asked to construct a finite automaton that accepts this language. We found that many students did not choose the easiest way to solve the problem: Many students preferred to construct a deterministic automaton, even though constructing a non-deterministic automaton for the language is much simpler. We analyze and categorize the students' solutions, thus shedding some light on their perception of the abstract concept of non-determinism.