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From Sean Owen <>
Subject Re: Understanding the SVD recommender
Date Thu, 03 Jun 2010 16:26:04 GMT
Section 3 is hard to understand.

- Ak and P are defined, but not used later
- Definition of P has UTk x Nu as a computation. UTk is a k x m
matrix, and Nu is "t" x 1. t is not defined.
- This only makes sense if t = m. But m is the number of users, and Nu
is a user vector, so should have a number of elements equal to n, the
number of items
- Sk * VTk is described as a k x "d" matrix but d is undefined
- The diagram suggests that VTk are multiplied by all the Nu, which
makes more sense -- but only if Nu are multiplied by VTk, not the
other way. And the diagram depicts neither of those.
- Conceptually I would understand Nu x VTk, but then P is defined by
an additional product with Uk

In short... what?

On Thu, Jun 3, 2010 at 4:15 PM, Ted Dunning <> wrote:
> Fire away.
> On Thu, Jun 3, 2010 at 3:52 AM, Sean Owen <> wrote:
>> Is anyone out there familiar enough with this to a) discuss this paper
>> with me or b) point me to another writeup on the approach?

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