Undue Influence: Eliminating
the Impact of Link Plagiarism
on Web Search Rankings
Baoning Wu and Brian D. Davison
Lehigh University
Symposium on Applied Computing 2006
Motivation

Link-based ranking algorithms are important
to current popular search engines. (e.g.,
HITS for Teoma)

Link farms will deteriorate the performance of
link-based ranking algorithms
HITS algorithm

Each page has two measures, authority
score a shows how good this page is for a
query, hub score h shows the possibility that
the page points to good authority pages. E is
the adjacency matrix.
a = ET h
h=Ea
Example: for query “weather”










http://www.tripadvisor.com/
http://www.virtualtourist.com/
http://www.abed.com/memoryfoam.html
http://www.abed.com/furniture.html
http://www.rental-car.us/
http://www.accommodation-specials.com/
http://www.lasikeyesurgery.com/
http://www.lasikeyesurgery.com/lasik-surgery.asp
http://mortgage-rate-refinancing.com/
http://mortgage-rate-refinancing.com/mortgagecalculator.html
Factors that degrade HITS

Mutually reinforcing relationships

Duplicate pages

Link farms
Complete hyperlink

Definition:


The link with its anchor text as a unit.
Duplication of a complete link is a much
stronger sign of copying behavior on the Web
than a duplicate link target.
Document - Complete link Matrix
Bipartite Graph

Two disjoint sets X and Y, each edge starts from an
element in X and ends with an element in Y.
Link farms

Link farms are usually densely connected via
multiple overlapping small bipartite cores.

Task: to detect densely connected bipartite
components from “document - complete link”
matrix
Algorithm for finding
bipartite components
Result: k=2 and l=2
Adjustment:
document-document matrix
Final matrix
Weighted adjacency matrix
Experiment:
HITS result of “rental car”










http://www.discountcars.net/
http://www.motel-discounts.com/
http://www.stlouishoteldeals.com/
http://www.richmondhoteldeals.com/
http://www.jacksonvillehoteldeals.com/
http://www.jacksonhoteldeals.com/
http://www.keywesthoteldeals.com/
http://www.austinhoteldeals.com/
http://www.gatlinburghoteldeals.com/
http://www.ashevillehoteldeals.com/
Experiment:
B&H HITS result of “rental car”










http://www.rentadeal.com/
http://www.allaboutstlouis.com/
http://www.allaboutboston.com/
https://travel2.securesites.com/
about_travelguides/addlisting.html
http://www.allaboutsanfranciscoca.com/
http://www.allaboutwashingtondc.com/
http://www.allaboutalbuquerque.com/
http://www.allabout-losangeles.com/
http://www.allabout-denver.com/
http://www.allabout-chicago.com/
Experiment:
CL-HITS result of “rental car”










http://www.hertz.com/
http://www.avis.com/
http://www.nationalcar.com/
http://www.thrifty.com/
http://www.dollar.com/
http://www.alamo.com/
http://www.budget.com/
http://www.enterprise.com/
http://www.budgetrentacar.com/
http://www.europcar.com/
Experiment:
B&H HITS result of “translation online”










http://www.no-gambling.com/
http://www.teleorg.org/
http://ong.altervista.org/
http://bx.b0x.com/
http://video-poker.batcave.net/
http://www.websamba.com/marketing-campaigns
http://online-casino.o-f.com/
http://caribbean-poker.webxis.com/
http://roulette.zomi.net/
http://teleservices.netfirms.com/
Experiment:
CL-HITS result of “translation online”










http://www.freetranslation.com/
http://www.systransoft.com/
http://babelfish.altavista.com/
http://www.yourdictionary.com/
http://dictionaries.travlang.com/
http://www.google.com/
http://www.foreignword.com/
http://www.babylon.com/
http://www.worldlingo.com/products_services
/worldlingo_translator.html
http://www.allwords.com/
Duplicate example:
BH-HITS result of “maps”










http://www.maps.com/
http://www.mapsworldwide.com/
http://www.cartographic.com/
http://www.amaps.com/
http://www.cdmaps.com/
http://www.ewpnet.com/maps.htm
http://mapsguidesandmore.com/
http://www.njdiningguide.com/maps.html
http://www.stanfords.co.uk/
http://www.delorme.com/
Duplicate example:
CL-HITS result of “maps”










http://www.maps.com/
http://maps.yahoo.com/
http://www.delorme.com/
http://tiger.census.gov/
http://www.davidrumsey.com/
http://memory.loc.gov/ammem/gmdhtml/gmdhome.html
http://www.esri.com/
http://www.maptech.com/
http://www.streetmap.co.uk/
http://www.libs.uga.edu/darchive/hargrett/maps/maps.html
User evaluation
Category
HITS
BHITS
CL-HITS CL-POP
Quite relevant
12.9%
24.5%
48.4%
46.3%
Relevant
10.7%
18.3%
28.8%
26.2%
Not sure
6.6%
10.5%
6.7%
6.4%
Irrelevant
26.8%
14.8%
11.3%
12.7%
Totally irrelevant
42.8%
31.9%
4.6%
8.1%
Discussion

Using link alone, the precision at 10 is 66.4%.
Much lower than using “complete link”.

Random anchor texts.

Questions?

baw4@cse.lehigh.edu
davison@cse.lehigh.edu
