# TU Wien:Semantic Web Technologies VU (Ortiz de la Fuente)

## Daten[edit]

Lecturers | Maria Magdalena Ortiz de la Fuente |
---|---|

ECTS | 3 |

Department | Logic and Computation |

Language | English |

Links | tiss:184729 , Mattermost-Channel |

## Inhalt[edit]

Block 1: querying graphs (3 lectures)

- Recap of relational data and queries
- Querying Graph-Structured data (RDF, property graphs, CQs, UCQs, RPQs)
- Querying RDF data with SPARQL

Block 2: querying knowledge graphs (4 lectures)

- RDF-S, completion rule algorithm
- OWL QL and Query Rewriting (PerfectRef)
- The OWL Profiles (OWL EL, RL, consequence-driven reasoning)
- The "big" OWL profiles (ALC-extensions, OWL 2 full, reduction of reasoning to KB (in-)consistency)

Block 3: beyond querying KGs (3 lectures)

- Inconsistency-tolerant quering (brave/cautious semantics etc)
- OBDA (Ontology-based data access) and Virtual KGs
- Constraints and SHACL (Shape Constraint Language for RDF)

## Ablauf[edit]

### WS20/21[edit]

One lecture per week (around 90 minutes on average), lecture videos are available on PeerTube. One exercise sheet per lecture (10 total).

The lectures can be handed in every Monday morning and are graded by Tuesday morning. On Tuesday mornings, there is a one-hour (Zoom) discussion of the material and exercise of the previous week and a look ahead on the week's material. Attendance is not mandatory, but recommended since Prof. Ortiz' explanations are quite helpful for the exercises and exam/quizzes.

Exercises are assessed on a scale "not assessable-progressing-mastered". There is no deadline for the exercises other than the final deadline at the end of January. This also means that exercises can be handed in multiple times to achieve a better exercise grade.

After each block, there is a TUWEL online quiz (MC/short open questions, always Tuesday mornings after the discussion). Previous quizzes can be retaken at each following quiz date, and also at the resit of the final exam in February.

There are two evaluation modes:

- Do all exercises, and pass all quizzes OR
- Only do the final exam (one date in January, one in February)

If you're unsatisfied with your exercise/quiz grade, you can still attempt the full exam.

In the exercise/quiz mode, the evaluation is by lecture block. The final grade is the average of the three block grades.

Grading scheme for the exercise/quiz format for each block:

- Grade 1: quiz 100-88% and all exercises mastered
- Grade 2: quiz 87.99-75% and all exercises assessed, at most one not yet mastered
- Grade 3: quiz 74.99-63% and all exercises assessed, at most two not yet mastered
- Grade 4: quiz 62.99-50% and all exercises assessed but one at least progressing.

It should be noted that the "bulk" of the lecture is in block 2, which is objectively more difficult than blocks 1 and 3.

## Benötigte/Empfehlenswerte Vorkenntnisse[edit]

Relational calculus, First-Order Logic, Complexity Theory basics as taught in e.g. TIL, DBS, ADBS, FMI, EWBS, KBS, DMOD etc.

Everything else is taught from the ground up, additional material is available if you're not familiar with the topics above.

It should be noted that the course is taught on a high-level, so don't expect to write "real implementations" except for a few simple SPARQL queries in block 2. It is also fairly theoretical, but nothing too complicated. The explanations in the video are also fairly high-level and in natural language.

## Vortrag[edit]

Asynchronous videos and weekly discussions. The slides for the lectures are also quite clean and are suitable as study material for the exam/quizzes. Note that not *everything* needed for the exams is written *explicitly* on the slides (but always implied), so it is recommended to watch the lecture/attend the discussion/think about the material a bit to fully understand the material.

There are also "learning objectives" (a set of questions) for each lecture, which are helpful when studying for the exam/quizzes or understanding the material in general. Additional sources for more in-depth information are also sometimes provided (sometimes just papers, so a TU VPN is needed to access the material).

The discussions are designed for the students to ask questions, so if something is unclear, Prof. Ortiz usually provides good explanations with small examples. If there are no questions, she usually highlights issues she saw in the exercises with examples.

## Übungen[edit]

One exercise sheet per week, Latex typesetting recommended/preferred. Latex source for the exercise sheet is always provided. About half a day for watching the lecture + doing the exercise.

The exercises are not too difficult, but do contain some pitfalls by design. Since exercises can be resubmitted until the end of the semester, this is not a big issue. I would recommend trying your best, and resubmitting if something is wrong or not fully correct. The exercise feedback is usually a few sentences per mistake/issue.

There is a reoccurring theme of re-using an application domain throughout the course. This application domain is extended/modified throughout, so a fitting domain is recommended. I would recommend a domain with four to five classes and two to three relations. Otherwise the domain is too simple/complicated and the exercises are a pain. The "classic" domain is the university domain, but you can choose anything you like as long as you're willing to work with it for a semester.

## Prüfung, Benotung[edit]

### Block/Exercise mode[edit]

For the quizzes, there is always a Zoom meeting you can join if you have questions. The quizzes are basically open-book (no weird room camera setups or anything else required), but this is no guarantee that you'll get a perfect score since a couple of questions aim for understanding of the topics at hand rather than MC on "what is on the lecture slides". The quizzes can also be re-taken multiple times, so there is no pressure on passing. The goal seems to be that the students understand the topics in the lecture.

### Full Exam mode[edit]

The full exam consists of two parts: A practical part (written) and a theoretical part (TUWEL quiz).

The exam starts with the practical part. For this, you have to join a Zoom meeting, verify your identity and keep the camera turned **on** for the written part, which takes 90 minutes. You can use a computer only for viewing the exam, the use of materials or outside help for the written part is not permitted. The exam should be written on a piece of paper. You are allowed to print out the exam and fill in the solutions in the gaps or write the solutions on a piece of paper if you don't have a printer available. After the 90 minutes, you have to scan the solution sheet(s) (phone or scanner) as one pdf and upload them to TUWEL. Afterwards, you can leave the Zoom meeting and do the theoretical part in the form of a TUWEL online quiz. The online quiz has a work time of 45 minutes, but is open for two hours (meaning you can take a break after the practical part).

### Dauer der Zeugnisausstellung[edit]

#### Block mode[edit]

Semester | Letzte Leistung | Zeugnis | |
---|---|---|---|

WS20 | 19.01.2021 | 19.01.2021 | same day (all exercises handed in before last quiz) |

## Zeitaufwand[edit]

Block or exercise/quiz mode:

- 10 exercises and lectures that take half a day/about 5 hours on average ~ 50 hours for the exercise
- 3 quizzes, about 7 hours prep for each should suffice for a good grade if you did the exercises diligently. ~21 hours quiz prep + 3 hours of quiz time.
- 10 optional discussions at 9 a.m. every Tuesday ~ 10 hours.

So in total a bit more than the 3 ECTS/75 hours foreseen for the course, but the gracious grading scheme takes off a lot of pressure to get everything right "the first time", so it does not feel that bad compared to other 3 ECTS courses.

## Unterlagen[edit]

noch offen

## Tipps[edit]

- Visit the discussions, if possible. Saves some time for doing the exercises/studying for the exam, and asking questions is always welcome.
- Use mattermost to discuss exercise solutions or lecture goal questions with your colleagues. There are also some discussions from past semesters.
- The block mode is more forgiving regarding the exam, considering you only have to do three quizzes. The exam mode seems harder, but could be more time-effective. However, it also depends on how much time you have at the end of the semester for studying for the full exam.
- The Latex templates for the exercises are okay, and contain some shortcut commands for the logic notation. You can use a Latex editor of your choice for the exercises, some previous knowledge of Latex might be helpful. Considering that all Bachelor's thesis at the faculty of informatics at TU Wien have to be written in Latex, this should not be a big issue.

## Verbesserungsvorschläge / Kritik[edit]

noch offen