# Automata Theory

In the lecture about theoretical computer science you have seen finite automata, pushdown automata and Turing machines. All three of them operate on finite words. However there are other automata models and automata that do not operate on finite words, but e.g. on infinite words, on nested words, on trees, etc. In this seminar we will have a look at automata models that you have not seen in the lecture on theoretical computer science. Additionally, we have a closer look at automata minimization.

Course type | Seminar |
---|---|

Instructors | Matthias Heizmann, Christian Schilling |

Kick-off meeting |
Mon 28.4.2014, 16:15-18:00, building 052, room 00-016 |

Presentations | weekly Mon 16:00 - 18:00, start on Mon 30.6.2014 |

Presentation language |
English |

Credits |
3 / 4 |

Course Catalog | Automata Theory (Master), Introduction to Automata Theory (Bachelor) |

## News

- Review partners have been assigned (section "Topics") and a schedule has been added.
- Please send us three topics ordered by your preferences until 8th May (Thursday).
- The presentations will be in June and July, each Monday there will be two presentations.
- Presentations are weekly on Mon 16:00 - 18:00.
- Available topics have been published. Please note that these are only suggestions, you may come up with your own topic as well.

## Process of the seminar

- Participate in the kick-off meeting, where we present the available topics. Feel free to hand in your favorite topic in advance.
- Contact Christian and Matthias to obtain a topic. You may suggest a topic by yourself, pick one of the suggested topics, or find a topic suitable for you in a discussion with Christian and Matthias.
- Have a meeting with Christian and Matthias in which we discuss relevant literature and develop a very coarse sketch of your talk. (in the first weeks of the semester).
- You write a proposal in which you explain what you are going to present in your talk.
- You write an abstract of your talk.
- You submit your abstract and your proposal via email to Christian and Matthias (deadline: three weeks before your talk).
- Your proposal is reviewed by two other participants.
- You write two reviews about other participants' proposals and send them via email to Christian and Matthias (deadline: one week after you received the proposal).
- You receive reviews of your proposal (deadline: two weeks before your talk).
- You submit your slides via email to Christian and Matthias (deadline: one week before your talk).
- You have a short meeting with Christian and Matthias in which you get feedback for your slides.
- You give a ca. 30 min talk (schedule see below).
- You attend the talks of all other participants.

## Proposals of the talk

The proposal should consist of around five pages in which you explain what you are going to present in your talk. The proposal may contain e.g.:

- short overview for the reviewers (the reviewers will probably not know your topic)
- structure of your talk
- aspects of the automaton class presented (why?) and ignored (why?)
- examples occurring in the talk (why these examples? Is there a running example that can be used for demonstration?)
- which definitions are presented formally? (why?), which definitions are just mentioned informally? (why?)
- which notation is used? (why?)
- which theorems are presented, which of them will be proven (why?), which proofs will be omitted (why?), will you use motivating examples in the proof?

## Abstract of the talk

- one paragraph that summarizes what you present in the talk
- We will send an invitation for the seminar to all students and members of our chair. This invitation contains the abstracts of all talks.

## The talk

- The goal of your talk is that the audience (master students, familiar with basic automata theory, probably no experts in the topic) has the possibility to learn something new about an interesting topic. How well you achieved this goal will determine the grade of your talk.
- In a seminar you have to show that you are able to present some topic to other people. You do not have to show how well you understood the topic for yourself. How well you understood the topic has no direct influence on your grade, but only how well you presented the topic to the audience.
- You may use and copy any source of information (but do not forget to cite it). If you think your talk is just a "remix" of existing talks tailored to your audience, you might have done a great job. But do not let yourself be fooled by well-structured and fancy talks found in the web, each talk was tailored to a specific audience.
- If you agree we put your slides on this website. Keep in mind that if you have copied images in your slides this might not be possible any more (copyright restrictions). Of course, it will not have any effect on your grade whether we may publish your slides or not.

## Review of the proposal

- Give a short summary of the talk based on the proposal (to detect misunderstandings right at the start).
- Be generous with your criticism. It is very unlikely that a student will get a bad grade because you revealed some problems in his/her talk. However, it is very likely that a student will get a better grade if he/she was able to resolve a problem in his/her talk, thanks to your review.
- Give reasons for your criticism (e.g., "It is not possible to understand Lemma 2 because term foo was not explained."). You are also allowed to give your personal opinions, if you do so mark them as such (e.g., "Theorem 1 is very difficult to understand, in my opinion you should give an example first.").
- The following questions might be helpful to write your review

Is the proposal sufficiently well written to be readable?

Is the appearance and structure of the proposal appropriate?

Is the comprehensibility of the talk supported by relevant examples and figures?

Is the proposed structure of the talk sensible and balanced?

Are all propositions made by the author correct?

Is the line of reasoning concerning the presentation complete and accurate?

Has the author argued his/her case effectively?

Does the author use the common notation and terminology? Where would you suggest something different?

Is the schedule of the author sensible? Do you think the talk will fit into the 30 min time slot?

## Grade

Your overall grade will be composed according to the following proportion.

- 10% grade of your proposal
- 20% grade of your reviews
- 70% grade of your talk

## Topics

### 30.6.2014 Nested word automata (Jens)

- Literature: Wikipedia, Nested words, Adding nesting structure to words
- Reviewers: Frank, Muhammed Said
- Slides: Nested word automata

### 30.6.2014 Tree automata (canceled)

- Literature: Wikipedia, TATA, Applied automata theory: chapter 3
- Reviewers: Göksu, Jens

### 7.7.2014 Omega automata I: Büchi automata (Muhammed Said)

- Literature: Wikipedia, Automata on infinte objects, Linear-time temporal logic and Büchi automata, ω-Automata, The complementation problem for Büchi automata with applications to temporal logic
- Reviewers: Claas, Göksu

### 7.7.2014 Omega automata II: other concepts (Göksu)

- Literature: Wikipedia, Automata and infinite words
- Reviewers: Muhammed Said, Thomas

### 14.7.2014 Alternating finite automata (Claas)

- Literature: Wikipedia, Weak alternating automata are not that weak
- Reviewers: Thomas, Tobias

### 14.7.2014 Star height (Thomas)

- Literature: Wikipedia, On the star height of rational languages. A new proof for two old results
- Reviewers: Claas, David
- Slides: Star height

### 28.7.2014 Hopcroft's DFA minimization algorithm (Tobias)

- Literature: Wikipedia, An n log n algorithm for minimizing states in a finite automaton (the site seems to be offline, ask us for a copy of the paper), Describing an algorithm by Hopcroft, Re-describing an algorithm by Hopcroft
- Reviewers: Aile, David

### 28.7.2014 Incremental DFA minimization (David)

- Literature:Incremental DFA minimization, An efficient incremental minization algorithm
- Reviewers: Jens, Tobias

### 28.7.2014 Tree automata (Aile)

- Literature: Wikipedia, TATA, Applied automata theory: chapter 3
- Reviewers: none

(For viewing some of the papers you may need to log in to the university network (f.i. via vpn) as they are not free.)

## Schedule

We have four meetings for the talks, hence four groups.

The following table contains the deadlines for the groups. Please note that "review" stands for the review deadline *for* the specific group. Each student has to write reviews for *two* groups.

date | proposal | review | slides | talk |
---|---|---|---|---|

9th June |
1 | |||

16th June | 2 | 1 | ||

23rd June | 3 | 2 | 1 | |

30th June | 3 | 2 |
1 | |

7th July |
4 | 3 | 2 | |

14th July | 4 | 3 | ||

21st July | 4 | |||

28th July | 4 |