FAdo 1 is an ongoing project which aims the development of an interactive environment for symbolic manipulation of formal languages. In this paper we focus in the description of interactive tools for teaching and assisting research on regular languages, and in particular finite automata and regular expressions. Those tools implement most standard automata operations, conversion between automata and regular expressions, and word recognition. We illustrate their use in training and automatic assessment. Finally we present a graphical environment for editing and interactive visualisation.

Visualization of computational models is at the heart of educational software for computer science and related elds. In this paper we look at how generation of such visualizations and the visualization of the generation process itself increase exploration. Four approaches of increased exploration in formal language theory and compiler design are introduced and for each approach we discuss an educational system which implements it. 1

We first give an overview of the features of the GANIMAL Framework introducing several new concepts not present in any previous algorithm animation system. Then we focus on its mechanisms for mixing live and post mortem visualization which are in particular very useful for algorithms which restructure graphs. 1

Introduction In previous articles we presented a PC based educational software on lexical analysis [1] and semantical analysis [4]. These systems were developed using an authoring system under MS Windows. The user can not change regular expressions or input words for nondeterministic respectively deterministic finite automata. To overcome these restrictions we developed GaniFA, our Java applet for visualization of algorithms from automata theory. It can be downloaded from our web page http://www.cs.uni-sb.de/GANIMAL as a JAR-file and requires a Java Plug-In 1.2. We invite the reader to use it in own web-based exercises, lecture notes or presentations on finite automata. Furthermore this web page gives a short overview, how this applet can be customized and embedded into HTML web pages. 2 GaniFA The GaniFA applet visualizes and animates the following algorithms [5]: -- Generation of a non-deterministic finite automaton (NFA) from a regular expression RE, see Figure 1. -- Removal of

Visualization of computational models is at the heart of educational software for computer science and related fields. In this paper we look at how generation of such visualizations and the visualization of the generation process itself increase explorativity. Four approaches of increased explorativity are introduced.

The use of generic and generative methods for the development and application of interactive educational software is a relatively unexplored area in industry and education. Advantages of generic and generative techniques are, among other things, the high degree of reusability of systems parts and the reduction of development costs. Furthermore, generative methods can be used for the development or realization of novel learning models. In this paper, we discuss such a learning model that propagates a new way of explorative learning in computer science education with the help of generators. A realization of this model represents the educational software GANIFA on the theory of generating finite automata from regular expressions. In addition to the educational system's description, we present an evaluation of this system.

FAdo is an ongoing project which goal is the development of a Python environment for manipulation of finite automata and regular expressions. Currently it provides most standard automata operations including conversion from deterministic to nondeterministic, minimisation, boolean operations, concatenation, conversion between automata and regular expressions, and word recognition. It includes, also, an innovative method for testing non-equivalence of two automata (or regular expressions) using a DFA canonical form and a witness generator of the difference of two automata.

In computer science methods to aid learning are very important, because abstract models are used frequently. For this conventional teaching methods do not suffice. We have developed a learning software, that helps the learner to better understand principles of compiler construction, in particular lexical analysis. The software offers on the one hand an interactive introduction to the problems of lexical analysis, in which the most important definitions and algorithms are presented in graphically appealing form. Animations show how finite automata are created from regular expressions, as well as, how finite automata work.

Abstract. We present an interactive graphical environment for the manipulation of context-free languages. The graphical environment allows the editing of a context-free grammar, the conversion to Chomsky normal form, word parsing and the (interactive) construction of parse trees. It is possible to store positive and negative datasets of words to be tested by a given grammar. The main goal of this system is to provide a pedagogical tool for studying grammar construction and parse trees. 1