Small-world connectorsSmall-world connectorsacross across

academic web spacesacademic web spaces

Lennart Björneborn

Royal School of Library and Information Science Copenhagen

lb@db.dk

AoIR-ASIST Workshop onWeb Science Research Methods

Association of Internet Researchers Conference, Brighton, UK

19 September 2004

M.C. Escher: House of Stairs, 1951

WWW = document network= collaborative weaving

Woo

d et

al.

(199

5)

3

web characteristicsweb characteristics

www = new type of document system

= no central control / coordination

= bottom-up construction

www = distributed knowledge organisation = ’3D’ = distributed + diversified + dynamic

www = individual input in collective medium

= collaborative weaving

www = self-organized macro-level aggregations (clusters) of micro-level interactions

www = local actions global consequences(e.g. small-world phenomena)

small-world networkssmall-world networks

small-world = highly clustered + short paths– short distances through shortcuts between nodes in network– small-world = short local + short global distances– efficient diffusion of signals, contacts, ideas, viruses, etc. in networks

social network analysis in 1960s: ’six degrees of separation’– today: ‘small worlds’ in biological, chemical, technical, social networks– brains, ecological food webs, scientific collaboration networks, etc.

Watts & Strogatz 1998

0

50

100

150

200

250

300

350

400

450

0 1000 2000 3000 4000 5000 6000 7000 8000

Subsites

In-n

eig

hb

ors

scale-free link distributionscale-free link distribution

power law = # in-neighbors / subsite

6

research motivationresearch motivation

distributed knowledge organization small world structures

exploratory capabilities (accessibility + navigability)

– core issues in LIS (library and information science)

– short link paths human web surfers + digital web crawlers can reach and retrieve web pages

what micro-level web activities contribute

to small-world link structures?

– how do academic link creators actually connect

documents, topics, genres, and sites across the Web?

7

main research questionmain research question what types of web links,

web pages and web sites

function as cross-topic connectors

in small-world link structures

across an academic web space?

webometricswebometrics

the study of quantitative aspects of

the construction and use of

info. resources, structures and technologies on the Web,

drawing on bibliometric and informetric approaches

informetrics

bibliometrics

scientometrics

webometrics

cybermetrics

© Björneborn 2004

basic link terminologybasic link terminology B has an inlink from A : ~ citation B has an outlink to C : ~ reference B has a selflink : ~ self-citation

E and F are reciprocally linked H is reachable from A by a link path A has a transversal link to G : shortcut

C and D have co-inlinks from B : ~ co-citation

B and E have co-outlinks to D : ~ bibliographic coupling

co-links

© Björneborn 2004

A

B

D

E G

F

H

C

UK link dataUK link data 20012001

109 UK universities 7669 subsites

– www.hum.port.ac.uk– www.atm.ox.ac.uk– ...

3.4 million web pages 39.3 mill. page outlinks

– 34.4 million site selflinks– 4.9 million site outlinks

delimited data set – 105 817 web pages– 207 865 links

between 7669 subsites

5-step methodology5-step methodologyA. Graph model of 7669 UK academic

subsites;

B. 189 random subsites in SCC(Strongest Connected Component);

C. 10 path nets with all shortest paths between five pairs of topically dissimilar SCC subsites;

D. Source and target pages along shortest link paths in 10 path nets;

E. Links, pages and subsites providing transversal (cross-topic) connections in 10 path nets.

A

CB

DE

corona modelcorona model1893 SCC

Strongest ConnectedComponent

96 IN-Tendrilsconnected from IN

2660 OUTreachable from SCC

626 INtraversable to

SCC

55 OUT-Tendrils connected to OUT

7 Tubeconnecting IN to OUT

2332 Dis-connected

© Björneborn 2004

bow-tie model

Broder et al. 2000

.ac.uk

.uk

cfd.me.umist.ac.uk

ercoftac.mech.surrey.ac.uk

cajun.cs.nott.ac.uk

ukoln.bath.ac.uk

cs.man.ac.uk

ashmol.ox.ac.uk

collections.ucl.ac.uk

vlmp.museophile.sbu.ac.uk

shortest shortest link pathlink path

© Björneborn 2004

path net = ‘mini’ small worldpath net = ‘mini’ small world

transversal link

path net = all shortest link paths between two given nodes (subsites)

© Björneborn 2004

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10 path nets10 path nets

hum.port.ac.uk

Faculty of Humanities and Social Sciences, Portsmouth

Atmospheric, Oceanic and Planetary Physics,

Oxford atm.ox.ac.uk

economics.soton. ac.ukEconomics Dept, Southampton

Chemistry Dept, Glasgow chem.gla.ac.uk

psy.man.ac.ukPsychology Dept, Manchester

Mathematics Dept, Glasgow Caledonian maths.gcal.ac.uk

speech.essex.ac.uk

Speech Research Group, Linguistics Dept, Essex

Palaeontology Research Group, Earth Sciences Dept, Bristol palaeo.gly.bris.ac.uk

geog.plym.ac.ukGeography Dept, Plymouth

Ophthalmology Dept,[eye research] Oxford eye.ox.ac.uk

5 pairs of topically dissimilar subsites

+ both directions

= 10 path nets with all shortest paths

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indicative findingsindicative findings no generalizable findings – indicative only

– national + sectoral + institutional delimitation = UK academic subsites

– temporal delimitation = 2001 snapshot : do not cover dynamic changes

– small stratified sample of 10 path nets

may however be fruitful for future large-scale investigations

– computer-science sites may be important transversal (cross-topic) connectors across academic web spaces

– personal link creators may be important connectors across sites and topics in academic web spaces – especially personal link lists

– over 80% of transversal links may be academic (research, teaching)

– close relation: hubs / authorities and betweenness centrality

web of genres & genre driftweb of genres & genre drift

© Björneborn 2004

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possible small-world implications/applicationspossible small-world implications/applications library and information science

– also focus on distributed knowledge organization (www)– also focus on exploratory capabilities in distributed info.systems

convergent (goal-directed) and divergent (serendipitous) info.behavior

web sociology / cyberscience– small-world links > cross-social / cross-domain weak ties– counteract balkanization into disconnected / unreachable insularities – small-world ‘gate-keepers’ with betweenness centrality in networks– tracking interdisciplinary boundary crossings– web mining of fertile areas for cross-disciplinary exploration

and cross-pollination

search engines– better coverage in web traversal + harvesting– zoomable maps of web clusters + small-world shortcuts

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Five ’laws’ of web connectivityFive ’laws’ of web connectivity– Links are for use – the very essence of hypertext;

– Every surfer his or her link– the rich diversity of links across topics and genres;

– Every link its surfer – ditto;

– Save the time of the surfer– by visualizing web clusters and small-world shortcuts;

– The Web is a growing organism.

Inspired by Ranganathan (1931). The five laws of library science:

“Books are for use.

Every reader his or her book.

Every book its reader.

Save the time of the reader.

The Library is a growing organism.”

© Björneborn 2004