Distributed Semantic
Associations
Matt Perry
Maciej Janik
Conrad Ibanez
Motivation
• Semantic Web, by its web nature is
distributed
• Knowledge will be stored in multiple
stores, multiple ontologies
• Search for semantic paths will have to
include many knowledge sources
Distributed ρ-path problem: Find
all paths from a start node to an end node
over the distributed RDF graphs
Knowledge bases - ontologies
border nodes
Assumptions
• K-hop limited ρ-path search
• Entity disambiguation across KBs
Problems
• Search Efficiency
• How to continue a search from one KB to
another
• When to stop a search in one KB and
start it in another
• How to piece together path fragments
Approach
KB
KB
Peer
Peer
Peer
KB
KB
Super-Peer
Peer
Super-Peer
Peer
Super-Peer
Peer
KB
Peer
Peer
KB
Peer
KB
KB
KB
Border Nodes
KB2
KB1
Border Node
Distance Between Borders
KB3
KB1
End
Dist(KB1KB2, KB1KB3) = 3
Dist(KB1KB2, KB2KB3) = 1
Dist(Start, KB1KB2) = 1
Dist(End, KB1KB3) = 1
KB2
Start
Query Plan Graph
Borders
AB
AC
BC
ABC
A
B
Minimum Distances
C
dist (AB, BC) = 4
dist (AB, AC) = 3
dist (AB, ABC) = 2
dist (BC, AC) = 5
dist (BC, ABC) = 3
dist (AC, ABC) = 2
dist (AB, AB) = 3
dist (AC, AC) = 3
dist (BC, BC) = 2
3
AB
2
3
4
ABC
Basic Idea:
2
1.
Add start and end node to QPG
2.
Do path search (<= K) through QPG
AC
3.
Convert the paths to a set of queries
3
3
5
BC
2
Converting Paths To Queries
Start
3
KB1/KB2
2
4
KB2/KB3
• ρ-path (Start, End, 12)
• KB1 – ρ-path (Start, KB1/KB2, 6)
• KB2 - ρ-path (KB1/KB2, KB2/KB3, 5)
• KB3 - ρ-path (KB2/KB3, End, 7)
End
Super-Peer Level QPG
Borders
AB
AC
BC
ABC
A/SP3
B/SP2
C/SP2
Super Peer 1
A
Minimum Distances
B
Super
Peer 3
C
Super
Peer 2
dist (AB, BC) = 4
dist (AB, AC) = 3
dist (AB, ABC) = 2
dist (BC, AC) = 5
dist (BC, ABC) = 3
dist (AC, ABC) = 2
dist (AC, A/SP3) = 3
dist (AB, A/SP3) = 4
dist (ABC, A/SP3) = 3
dist (AC, C/SP3) = 2
dist (BC, C/SP3) = 4
dist (ABC, C/SP3) = 2
dist (AB, B/SP2) = 2
dist (BC, B/SP2) = 4
dist (ABC, B/SP2) = 5
Integration of SP graph and Peer
Graph
4
A/SP3
3
2
AB
B/SP2
3
4
2
5
ABC
3
0
0
4
2
SP1/SP3
3
5
AC
2
BC
2
4
0
C/SP3
SP1/SP2
Whole Process
1. Peer asks SP for Query Plan
2. SP finds endpoints and adds them to SP QPG
3. SP finds all Paths through SP QPG
4. SP converts these Paths in subquery plan
requests for each SP
5. Each SP uses the process recursively on its
peer-level QPG to form peer-level query plan
6. The union of the peer-level query plans is
the final query plan
7. The peer then executes this plan
Test sets
Border 1/2/3
Team 8286
Test 3
Test 1
Agent 2054
Athlete 6988
Agent 2054
Athlete 2805
Agent 2457
Athlete 4343
Agent 2054
Agent 566
Athlete 7028
Test 2
Athlete 3108
Agent 2418
Agent 717
Team 8430
Agent 717
Athlete 6041
Agent 2215
Athlete 6778
Agent 1194
Agent 2215
Border 1/2
Athlete 2951
Team 8405
Agent 1808
Agent 1632