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From "Stephen Allen (JIRA)" <>
Subject [jira] [Commented] (JENA-242) LARQ scores not normalized
Date Thu, 03 May 2012 19:18:49 GMT


Stephen Allen commented on JENA-242:

I haven't really had a chance to use LARQ much, but I'm not sure that normalizing the scores
is necessarily the best thing to do.  It makes a bunch of assumptions (underlying data isn't
changing, that there is a linear relationship between scores, that scores mean something across
queries, etc).  Importantly, as the scores between different queries are not related to each
other, an arbitrary value for the FILTER clause doesn't make sense.  If the result of your
query was a bunch of really bad matches, but they all had the same score, then they'd show
up as 100% relevance, and then pass your filter (see [1]).

Instead, I think you should use ORDER BY on the score, and then maybe LIMIT the results to
a subset.  Or if you really must have a normalized result, then retrieve all the results and
calculate the normalized score in your application (although I encourage you not to).  More
info about scoring at [2].


> LARQ scores not normalized
> --------------------------
>                 Key: JENA-242
>                 URL:
>             Project: Apache Jena
>          Issue Type: Bug
>          Components: LARQ
>    Affects Versions: LARQ 1.0.0
>         Environment: Fuseki
>            Reporter: laotao
> In previous versions the LARQ score seemed to be normalized to range [0, 1]. In LARQ
1.0.0 some scores can be higher than 1. 
> Normalized scores are needed to filter sparql results (so that only items above certain
quality is shown).

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