Remaining Lectures (Notice Changes!)
Following our discussion in the Sunday lecture this week, the remaining lectures of the semester will be given in the next two weeks, as follows:
1. L10: Sunday, Dec 30, 13:30-15:30: Ulman 702
2. L11: Sunday, Dec 30, 16:30-18:30: Ulman 102
3. L12: Sunday, Jan 6, 13:30-15:30: Ulman 702
4. L13: Sunday, Jan 6, 16:30-18:30: Ulman 102
Update of Assignment 3, Q2.2
|In Part 2 of Question2, I've added a restricting assumption that no relation symbol occurs more than once in all of the queries (and not just in each individual query).|
Leonid Libkin's Guest Lecture (Sunday, 23/12, 13:30, 702 Ulman)
|Title: Incomplete information in databases: history as it should have been, and a possible future|
It is very well known that relational database queries produce incorrect results when applied to incomplete data. Theoretical notions of correctness carry a huge complexity price - hence practical solutions ought to do something different. Databases that speak SQL use a three-valued logic to handle incompleteness; this is efficient, but incorrect answers can be produced.
Over two hours we'll try to answer two questions: 1) was the three-valued logic really necessary? and 2) how bad are query answers that relational databases produce? For the first, we re-examine the reasoning that went into using the three-valued logic and try to think what could or should have been done instead. For the second, unlike the standard approach to querying incomplete data that relies on the notion of certainty of answers, we instead measure how close an answer is to certainty. Techniques for doing this, related to the study of 0-1 laws and asymptotic properties of logical sentences, may offer a possible way of bridging the gap between efficiency and correctness.
Leonid Libkin is Professor of Foundations of Data Management in the School of Informatics at the University of Edinburgh. He was previously a Professor at the University of Toronto and a member of research staff at Bell Laboratories in Murray Hill. He received his PhD from the University of Pennsylvania in 1994. His main research interests are in the areas of data management and applications of logic in computer science. He has written five books and over 200 technical papers. His awards include a Royal Society Wolfson Research Merit Award, a Marie Curie Chair Award, and five Best Paper Awards. He has chaired programme committees of major database conferences (ACM PODS, ICDT) and was the conference chair of the 2010 Federated Logic Conference. He has given many invited conference talks and has served on multiple program committees and editorial boards. He is an ACM fellow, a fellow of the Royal Society of Edinburgh, and a member of Academia Europaea.
Assignment 3 is Published
|Note: this is a short assignment with a close due date: December 20th.|
Today's Lecture at Amado 300 (9/12, 13:30)
|Today's lecture (Sunday 09/12, 13:30) is unusually at Amado 300. |
Make-up Lecture 9:30 Tomorrow (Sunday), Taub 301
|I remind you about the make-up lecture tomorrow (Sunday 09/12), 9:30, in Taub 301.|
Changes in Schedule
(1) Recall that there is no lecture on December 2, due to Hanukkah (and anyway the day operates on Tuesday mode).
(2) The lecture on Sunday 16/12 is cancelled, since I need to attend a whole-day seminar.
(3) I will give a replacement lecture on Sunday 09/12, 9:30.
Therefore, on Sunday 09/12 there will be two lectures: 9:30-11:30 and the usual 13:30-15:30.
Reminder: Today's Lecture (Nov 4) is Canceled
|Please be reminded that today's lecture (04/11) is canceled. |
Makeup Lesson Sunday Oct 28, 9:30, Taub 301
|I will give a makeup lesson, to replace the canceled lecture on November 4.|
Oct 28, 2018
Connect to the course calendar: