Matrix Factorization with Implicit Feedback

[Royi Ronen]

Hi,

I am looking for confirmation regarding my usage of Mahout matrix
factorization with implicit feedback.
The input file is of the form <user,item,1> , as advised in one of the
Mahout forums.
All my usage points are positive (i.e, the user watched the movie).

I changed the MovieLens Example:

$MAHOUT parallelALS --input /tmp/mahout-work-cloudera/input.txt --output
${WORK_DIR}/als/out \
    --tempDir ${WORK_DIR}/als/tmp --numFeatures 20 --numIterations 40
--lambda 0.065 --implicitFeedback true

# compute recommendations
$MAHOUT recommendfactorized --input ${WORK_DIR}/als/out/userRatings/
--output ${WORK_DIR}/recommendations/ \
    --userFeatures ${WORK_DIR}/als/out/U/ --itemFeatures
${WORK_DIR}/als/out/M/ \
    --numRecommendations 10 --maxRating 5


This runs OK and gives recommendations that sometimes seem to be biased
towards popular items.
I would like to verify that this is the right way to run it.

Also - does anyone know which algorithm is used to factorize?

Thanks very much :)