CS 451 Quiz 24
Recommender systems and collaborative filtering
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According to Andrew Ng, recommender systems
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1 point
receive much attention in academia but are not widely used in industry
receive relatively little attention in academia, but are widely used in industry
Suppose user j has watched movie i and rated it 4 out of 5. Which of the following describes this scenario?
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1 point
r(i, j) = 0 and y(i, j) = 4
r(i, j) = 1 and y(i, j) = 4
r(i, j) = 4 and y(i, j) = undefined
r(i, j) = 4 and y(i, j) = 5
To learn the movie ratings for user j, we can use
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1 point
linear regression over all movies i
linear regression over all movies i for which r(i, j) = 1
logistic regression over all movies i
logistic regression over all movies i for which r(i, j) = 1
Collaborative filtering is an algorithm for
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1 point
classification
clustering
density estimation
feature learning
One way to implement collaborative filtering is to alternate estimating theta's from x's, and x's from theta's. Which of the following algorithms operates in a similar way?
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1 point
Knearest neighbors
Kmeans
PCA
Instead of alternating the two estimation problems, we can estimate x's and theta's jointly in a single minimization problem.
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1 point
True
False
Why do we initialize x's and theta's to small random values?
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1 point
This step is optional. Initializing to all 0's would work just as well.
Random initialization is always necessary when using gradient descent
This ensures that x(i) != theta(j) for any i, j
For symmetry breaking, so the algorithm can learn features that are different from each other
In collaborative filtering we don't need to include "bias" features x0 = 1 and theta0 = 1
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1 point
True
False
Which of the following is NOT one of movie titles used as examples?
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1 point
Romance forever
Swords vs. karate
Hot wheels of fire
Cute puppies of love
What comes to mind when you see this?
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1 point
Impressive!
Scary!
Math is fun!
These Romans are crazy!
Other:
HW 5 teams [not graded]
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Please enter one of "working with [your partners name]", "working alone", or "still looking for a partner"
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