Distributed Semantic Associations

1
Distributed Semantic Associations

• Matt Perry
• Maciej Janik
• Conrad Ibanez

2
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

3
Distributed ?-path problem Find all paths from a
start node to an end node over the distributed
RDF graphs
Knowledge bases - ontologies
4
Assumptions

• K-hop limited ?-path search
• Entity disambiguation across KBs

5
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

6
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
7
Border Nodes
KB2
KB1
Border Node
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Distance Between Borders
KB3
KB1
End
Dist(KB1KB2, KB1KB3) 3 Dist(KB1KB2, KB2KB3)
1 Dist(Start, KB1KB2) 1 Dist(End, KB1KB3) 1
KB2
Start
9
Query Plan Graph

• Basic Idea
• Add start and end node to QPG
• Do path search (lt K) through QPG
• Convert the paths to a set of queries

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Converting Paths To Queries
4
3
Start
2
KB1/KB2
KB2/KB3
End

• ?-path (Start, End, 12)
• KB1 ?-path (Start, KB1/KB2, 6)
• KB2 - ?-path (KB1/KB2, KB2/KB3, 5)
• KB3 - ?-path (KB2/KB3, End, 7)

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Super-Peer Level QPG
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Integration of SP graph and Peer Graph
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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

14
Test sets
Border 1/2/3
Test 3
Test 1
Team 8286
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
Agent 1632
Border 1/2
Athlete 2951
Team 8405
Agent 1808