3 research outputs found
Automata Tutor v3
Computer science class enrollments have rapidly risen in the past decade.
With current class sizes, standard approaches to grading and providing
personalized feedback are no longer possible and new techniques become both
feasible and necessary. In this paper, we present the third version of Automata
Tutor, a tool for helping teachers and students in large courses on automata
and formal languages. The second version of Automata Tutor supported automatic
grading and feedback for finite-automata constructions and has already been
used by thousands of users in dozens of countries. This new version of Automata
Tutor supports automated grading and feedback generation for a greatly extended
variety of new problems, including problems that ask students to create regular
expressions, context-free grammars, pushdown automata and Turing machines
corresponding to a given description, and problems about converting between
equivalent models - e.g., from regular expressions to nondeterministic finite
automata. Moreover, for several problems, this new version also enables
teachers and students to automatically generate new problem instances. We also
present the results of a survey run on a class of 950 students, which shows
very positive results about the usability and usefulness of the tool
Comparison of Algorithms for Simple Stochastic Games (Full Version)
Simple stochastic games are turn-based 2.5-player zero-sum graph games with a
reachability objective. The problem is to compute the winning probability as
well as the optimal strategies of both players. In this paper, we compare the
three known classes of algorithms -- value iteration, strategy iteration and
quadratic programming -- both theoretically and practically. Further, we
suggest several improvements for all algorithms, including the first approach
based on quadratic programming that avoids transforming the stochastic game to
a stopping one. Our extensive experiments show that these improvements can lead
to significant speed-ups. We implemented all algorithms in PRISM-games 3.0,
thereby providing the first implementation of quadratic programming for solving
simple stochastic games