Differences between revisions 31 and 345 (spanning 314 versions)

Welcome to the Wiki page of the course Search Engines, WS 2009 / 2010. Lecturer: Hannah Bast. Tutorials: Marjan Celikik. Course web page: click here.

Here are PDFs of the slides of the lectures so far: Lecture 1, Lecture 2, Lecture 3, Lecture 4, Lecture 5, Lecture 6.

Here are .lpd files of the recordings of the lectures so far (except Lecture 2, where we had problems with the microphone): Recording Lecture 1, Recording Lecture 3, Recording Lecture 4, Recording Lecture 5 (no audio), Recording Lecture 6 (with audio for a change).

Here are PDFs of the exercise sheets so far: Exercise Sheet 1, Exercise Sheet 2, Exercise Sheet 3, Exercise Sheet 4, Exercise Sheet 5, Exercise Sheet 6.

Here are your solutions and comments on the previous exercise sheets: Solutions and Comments 1, Solutions and Comments 2, Solutions and Comments 3, Solutions and Comments 4, Solutions and Comments 5.

Exercise Sheet 6

The recordings of all lectures are now available, see above. Lecture 2 is missing because we had technical problems there. To play the recordings (it's .lpd files) you need the Lecturnity Player. You can download the player for free here.

Here are the rules for the exercises as explained in Lecture 2.

Here you can upload your solutions for Exercise Sheet 6.

Questions or comments below this line, most recent on top please

Notice about Problem 2: You should use precise timers when measuring the running times. If your collection is very small and you round up your times, it's easy to get 0 ms when merging or scanning the inverted lists. I recommend using microsecond scale. Marjan 29Nov09 16:47

To Florian: Yes, you can do anything you want to find those words (as long as you produce the required outputs). Marjan 29Nov09 16:44

For exercise 1, should we use one of the methods presented in the lecture to find all words in the collection with the prefixes or can we do just anything to get them (though it might not be as efficient)? Florian 29Nov09 03:51pm

When you scan, please make sure that you do something very simple with the elements, like summing up all doc ids, and then outputting that sum. Otherwise a clever compiler might figure out that it can remove the whole loop, because it is not producing a result that is used anywhere. Hannah 28Nov09 11:48pm

To Mirko: Yes, scanning means one pass over the elements. Marjan 28Nov09 19:19

Hi, about exercise2: is by "scanning" meant that one looks at every element exactly once? (=> costs of scanning a list are just the size of the list) Mirko 28Nov, 19:12

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-= Exercise Sheet 1 =
[[attachment:SearchEnginesWS0910/ExerciseSheet1/lecture-1.ppt|Here are the PPT slides of Lecture 1]].
+Here are PDFs of the slides of the lectures so far: [[attachment:SearchEnginesWS0910/lecture-1.pdf|Lecture 1]], [[attachment:SearchEnginesWS0910/lecture-2.pdf|Lecture 2]], [[attachment:SearchEnginesWS0910/lecture-3.pdf|Lecture 3]], [[attachment:SearchEnginesWS0910/lecture-4.pdf|Lecture 4]], [[attachment:SearchEnginesWS0910/lecture-5.pdf|Lecture 5]], [[attachment:SearchEnginesWS0910/lecture-6.pdf|Lecture 6]].
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-[[attachment:SearchEnginesWS0910/ExerciseSheet1/exercise-1.pdf|Here is a PDF of Exercise Sheet 1]].
+Here are .lpd files of the recordings of the lectures so far (except Lecture 2, where we had problems with the microphone): [[http://vulcano.informatik.uni-freiburg.de/lecturnity/lecture-1.lpd|Recording Lecture 1]], [[http://vulcano.informatik.uni-freiburg.de/lecturnity/lecture-3.lpd|Recording Lecture 3]], [[http://vulcano.informatik.uni-freiburg.de/lecturnity/lecture-4.lpd|Recording Lecture 4]], [[http://vulcano.informatik.uni-freiburg.de/lecturnity/lecture-5.lpd|Recording Lecture 5 (no audio)]], [[http://vulcano.informatik.uni-freiburg.de/lecturnity/lecture-6.lpd|Recording Lecture 6 (with audio for a change)]].
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-[[SearchEnginesWS0910/StudentIntros|Introduce yourself on this page please (Exercise 1)]].
+Here are PDFs of the exercise sheets so far: [[attachment:SearchEnginesWS0910/exercise-1.pdf|Exercise Sheet 1]], [[attachment:SearchEnginesWS0910/exercise-2.pdf|Exercise Sheet 2]], [[attachment:SearchEnginesWS0910/exercise-3.pdf|Exercise Sheet 3]], [[attachment:SearchEnginesWS0910/exercise-4.pdf|Exercise Sheet 4]], [[attachment:SearchEnginesWS0910/exercise-5.pdf|Exercise Sheet 5]], [[attachment:SearchEnginesWS0910/exercise-6.pdf|Exercise Sheet 6]].
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-[[SearchEnginesWS0910/ExerciseSheet1|Upload your results to Exercise Sheet 1 on this page please]].
+Here are your solutions and comments on the previous exercise sheets: [[SearchEnginesWS0910/ExerciseSheet1|Solutions and Comments 1]], [[SearchEnginesWS0910/ExerciseSheet2|Solutions and Comments 2]], [[SearchEnginesWS0910/ExerciseSheet3|Solutions and Comments 3]], [[SearchEnginesWS0910/ExerciseSheet4|Solutions and Comments 4]], [[SearchEnginesWS0910/ExerciseSheet5|Solutions and Comments 5]].

= Exercise Sheet 6 =
The recordings of all lectures are now available, see above. Lecture 2 is missing because we had technical problems there. To play the recordings (it's .lpd files) you need the Lecturnity Player. [[http://www.lecturnity.de/de/download/lecturnity-player|You can download the player for free here]].

[[SearchEnginesWS0910/Rules|Here are the rules for the exercises as explained in Lecture 2]].

[[SearchEnginesWS0910/ExerciseSheet6|Here you can upload your solutions for Exercise Sheet 6]].
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-Please note that the deadline for uploading your solutions of the exercises is always Monday, 23:59 (sharp). '''Marjan 22Oct09 6:15pm'''
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-When you add a question or comment here, please end it with your name and the date and time in bold face, just like I did now. '''Hannah 22Oct09 01:59am'''
+Notice about Problem 2: You should use precise timers when measuring the running times. If your collection is very small and you round up your times, it's easy to get 0 ms when merging or scanning the inverted lists. I recommend using microsecond scale. '''Marjan 29Nov09 16:47'''
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-Can you provide the slides as PDF? '''Johannes 23Oct09 10:05am'''
+To Florian: Yes, you can do anything you want to find those words (as long as you produce the required outputs). '''Marjan 29Nov09 16:44'''

For exercise 1, should we use one of the methods presented in the lecture to find all words in the collection with the prefixes or can we do just anything to get them (though it might not be as efficient)? '''Florian 29Nov09 03:51pm'''

When you scan, please make sure that you do something very simple with the elements, like summing up all doc ids, and then outputting that sum. Otherwise a clever compiler might figure out that it can remove the whole loop, because it is not producing a result that is used anywhere. '''Hannah 28Nov09 11:48pm'''

To Mirko: Yes, scanning means one pass over the elements. '''Marjan 28Nov09 19:19'''

Hi, about exercise2: is by "scanning" meant that one looks at every element exactly once? (=> costs of scanning a list are just the size of the list) '''Mirko 28Nov, 19:12'''