Lots of large special interest Linked Data, but don't want to completely discount them.
What does the average user want from Linked Data?Hypothesis: We can sample a hypertext query log and run it against a Linked Data search engine.
Entities The gazetteer for names was based on a list of names maintained by the Social Security Administration and the gazetteer for place names was based on the gazetteer provided by the Alexandria Digital Library Project, plus some rules for capitalization etc.
High precision, low recall: Best system at MUC-7, around 94% correct (entities) to 98% correct (concept) over 100 random samples.Concepts: Restrict to single terms with both hypernym and hyponym in WordNet
Data Set: Microsoft Live Search Query Log for 1 month from 2007
Entity Queries: alpha = 2.31, with long tail behavior starting around a frequency of 17 and a Kolmogorov-Smirnov D-statistic of .0241, indicating a significant good fit.
Concept Queries: The alpha= of the queries for concept queries was calculated to be 2.12, with long tail behavior starting around a frequency of 36 with a Kolmogorov-Smirnov D-statistic of .017.
Question: Is the amount of Linked Data returned correlated with the popularity of the query?
No: Spearman's rank correlation statistic was the insignificant .0077 ($p > .05), while for concept queries, the correlation was the still insignificant at .0125 ($p > .05$)
What URIs did the data come from?
There are too many URIs for the same thing probably...
An average of 1,339 URIs (S.D. 8,000) returned per query. That's a lot, but most may obviously be URIs that just mention the term...
The majority of URIs, 51,873 (74%), served RDF via 303 redirection.
200 status codes without 303 redirection still form a substantial fraction (9%) of Semantic Web URIs - URIs just served not as Linked Data.All hash convention URIs would by default still technically commit a redirect to be served by a 200 status code.
This is only a minority (27%) of those URIs returning a 200 status code.The rest are likely caused by people serving RDF that does not have the access to the Web server configuration needed to serve RDF using 303 redirection.
| Number | Percent | Status Code |
| 51,873 | 73.97% | 303 |
| 6,061 | 8.65% | 200 |
| 4,517 | 6.44% | 404 |
| 4,257 | 6.07% | 500 |
| 3,147 | 4.49% | 300 |
| 246 | 0.35% | 406 |
| 20 | 0.03% | 403 |
| 4 | 0.00% | 302 | 3 | 0.00% | 502 |
Some URIs were inaccessible, this reduced size of sample to 60,972, a reduction of (13%) from the crawled URIs.
The accessible crawled URIs contained 24,074 accessible crawled concept URIs (95% of all crawled concept URIs) and 36,898 (82% of all crawled entity URIs) accessible crawled entity URIs.
Each of the crawled accessible URIs was accessed, and this resulted in a total of 59,228 Semantic Web documents with only 48 URIs not allowing access to a Semantic Web document.| Number | Percent | Vocab URI |
| 366,849 | 33.55% | DBpedia URIs |
| 109,300 | 9.99% | RDF URIs |
| 100,340 | 9.17% | RDF(S) URIs |
| 94,520 | 8.65% | Cyc URIs |
| 34,136 | 3.12% | OWL URIs |
| 6,563 | 0.60% | SKOS URIs |
| 4,728 | 0.43% | dblp.l3s.de URIs |
| 3,263 | 0.29% | FOAF URIS |
| 2,170 | 0.20% | YAGO URIs |
| 1,836 | 0.16% | WordNet URIs |
A total of 411,574 RDF triples in the crawled triples, with 242,829 (59%) triples for concepts and 168,745 (41%) triples for entity URIs.
Of these triples, there were a total of 1,051 triples containing blank nodes, a measly .25% of all triples in the corpus, of which 772 (73%) were subjects and only 279 (27%) were in the object position.This means that the use of blank nodes are almost non-existent in our sample.
Removing blank nodes, the composition was split between URI nodes (66%) and a surprisingly large minority of RDF literals nodes (34%).Of the literals, a total of 403,119 (almost 98%) were RDF string literals, while only 2% were of some other data type.
| 403,119 | 97.95% | RDF plain literal |
| 3,103 | 0.75% | w3c:/XMLSchema#integer |
| 2,789 | 0.68% | w3c:/XMLSchema#string |
| 1,185 | 0.29% | w3c:/XMLSchema#double |
| 522 | 0.13% | w3c:/XMLSchema#date |
| 248 | 0.06% | w3c:/XMLSchema#float |
| 136 | 0.03% | w3c:/XMLSchema#gYear |
| 65 | 0.02% | w3c:/XMLSchema#gYearMonth |
| 59 | 0.01% | dbpedia:Rank |
| 46 | 0.01% | dbpedia:Dollar |
| 14 | 0.00% | w3c:/XMLSchema#int |
| 9 | 0.00% | dbpedia:Percent |
The usage of OWL, RDF(S), and RDF terms does not form a power law. This is because while a few terms vastly dominate, the vast majority of other terms are not used at all.
| Number | Percent | Language Construct |
| 73,451 | 30.31% | rdfs:Class |
| 47,044 | 19.30% | rdfs:comment |
| 44,113 | 18.10% | rdfs:subClassOf |
| 8,630 | 3.54% | owl:Ontology |
| 7,256 | 2.97% | rdfs:label |
| 6,618 | 2.14% | rdf:Subject |
| 5,107 | 2.09% | owl:ObjectProperty |
| 3,642 | 1.49% | rdfs:subPropertyOf |
| 1,157 | 0.47% | owl:sameAs |
| 535 | 0.29% | rdfs:range |
One of the most popular OWL constructs is indeed the controversial owl:sameAs term used to declare equivalence.
One critique holds that it is declaring equivalence between things that are not equivalent, so equivalence is being used too much.Only 47% of overall Semantic Web modelling term usage, it is far from insignificant, with 1,157 occurrences.
Given the amount of Semantic Web URIs returned by the queries, it appears that the manual discovery and publication of co-referential URIs using owl:sameAs falls far behind the actual growth of Linked Data.Surprise! Likely owl:sameAs is not being used enough.
The Linked Data Web is full of interesting structured data, but mostly on DBpedia.
Most Linked Data seems to actually conform to the 303 redirect and other recommendations (...or is that mostly DBpedia?)There is a lot of potential information that users may be interested in! So lots of work needs to be done on ranking linked data.
Yet is this data really relevant to the user's needs? How many are returned in are irrelevant. This is in my SemSearch2009 paper.How badly biased is this sample by the use of FALCON-S? Can we repeat it using other search engines?
Can we more fairly sample Linked Data while excluding semantic spam or just irrelevant and useless data?Results of Relevance Judgements:
| Results: | Hypertext | Semantic Web | Resolved: | 197 (98%) | 132 (66%) | Unresolved: | 3 (2%) | 68 (34%) | Top Relevant: | 121 (61%) | 76 (58%) |
| Top Non-Relevant: | 76 (39%) | 56 (42%) |

Results of Querying the Hypertext Web

Results of Querying the Semantic Web