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OWL-Gres vs Quonto. Angela Alvarez Rubio. Introduction. Using ontologies as a conceptual point of view on repositories of data is increasingly. These ontologies deal with large amounts of data. Most important parameter on computational complexity of reasoning. Data size.

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Owl gres vs quonto

OWL-Gres vs Quonto

Angela Alvarez Rubio


Introduction
Introduction

  • Using ontologies as a conceptual point of view on repositories of data is increasingly

  • These ontologies deal with large amounts of data

  • Most important parameter on computational complexity of reasoning

  • Data size

  • We will want a polynomial reasoning!

  • And we want can do complex questions


Introduction1
Introduction

  • 2 stapes:

  • 1. Perfect reformulation: taking into account the TBOX T, the q query is reformulated in a new query

  • On a DL-Lite

  • Conjunctive query is a union of conjunctive wich size does not depend on A

  • We can evaluate it with LOGSPACE on the ABOX size


Introduction2
Introduction

  • 2 stapes:

  • 2. Query Evaluation: the new query is evaluated only in the ABox to produce the answer

  • The ABox, is maintained through a RDBMS (Data management systems relational) in the secondary storage to control a large data number

  • Because is the unique tecnology

  • The evaluation of the query can be delegated to an engine SQL database with optimization of querys strategies


Introduction3
Introduction

  • We presented two systems to work with large amounts of data:

  • OWL-Gres

  • Quonto


Introduction4
Introduction

  • Targets

  • Discover the DL-Lite fragment in which is based in OWL_Gres

  • Compare the OWL-Gres system with Quonto system


Quonto
Quonto

  • Is a tool that implements the DL-Lite query answering algorithm

  • Delegates to a RBDMS the storing of the ABOX

  • Is capable of answering questions about ABOXes wich containing millions of assertions

  • Their limitations will depend of the single engine DBM


Quonto dl lite a
Quonto: DL-Lite A+

  • Is the fragment DL-Lite largest known in order to obtain LOGSPACE data complexity

  • Represents the domain in terms of concepts, sets of objects, and roles and permets:

  • Value-Domains: domains that denote specific sets of values (data)

  • Concept attributes: binary relations between objects and values

  • Role attributes: ternary relations between pairs of objects and value

  • Enjoys FOL-rewritability

  • Allows for functionality assertions and role inclusion assertions, but with some restrictions:

  • No functional role or attribute can be specialized by using it in the right-hand side of a role or attribute inclusion assertions


Quonto dl lite a1
Quonto: DL-Lite A+

  • Concept inclusion assertion: B ⊑ C

The knowledge base (KB) is formed by:

  • Attribute inclusion assertion: U ⊑ V

  • T: TBOX to represent intensional knowledge

  • Value-domain inclusion assertion: E ⊑ F

  • Role inclusion assertion: Q ⊑ R

  • Attribute functionality assertion: funct U

  • Role functionality assertion: funct Q

  • Attribute Role: funct R

K=<T, A>

  • A: ABOX to represent extensional knowledge

  • Member Assertions

A(c), P(c; c0),

UC(c; d) UR(a, b, c)


Quonto query answering
Quonto:Query answering

  • Query conjunctive in a KB K:

  • Union of conjunctive queries (UCQ):

  • x: Distinguished variables

  • y: Non-distinguished variables

  • conj (x, y): atoms:

    • A(xo)

    • P(xo, yo)

    • D(xv)

    • UC(xo,xv)

    • UR(xo,y0 xv)

q(x) ←y. conj(x,y)

  • xo, yo are variables in x and y or constants in ГO

  • xv is a variable in x and y a constant in ГV

Certain answers all tuples t of elements of ГV ГO such that, when substituted to x in q(x), we have that K |= q(t)

q(x) ←Viyi. conj(x,y)


Firs target
Firs Target

  • On what DL-Lite fragment is based OWL-Gres?

  • See the characteristics of potential fragments and differentiate it

  • 2 steps:

  • Java Program

  • See if OWL-Gres accept this characteristics

  • Protege tool


First target fragments
First Target: Fragments


First target fragments1
First Target: Fragments


First target fragments2
First Target: Fragments


First target fragments3
First Target: Fragments


First target fragments4
First Target: Fragments


First target fragments5
First Target: Fragments


First target fragments6
First Target: Fragments


First target search
First Target: Search

  • We use a TBOX based in the university hierarchy:


First target search1
First Target: Search

  • Initially our TBOX is compatible with OWL-Gres:

C:\Documents and Settings\Propietario\workspace\OwlGres

21-jul-2008 12:54:42 org.coode.owl.rdfxml.parser.OWLRDFConsumer endModel

INFO: Total number of triples: 617

21-jul-2008 12:54:42 org.coode.owl.rdfxml.parser.OWLRDFConsumer endModel

INFO: Loaded http://semantics.crl.ibm.com/univ-bench-dl.owl

The TBox is compatible with DL-Lite


First target search2
First Target: Search

  • We verify for DL-Lite F:


First target search3
First Target: Search

  • We verify for DL-Lite F:

C:\Documents and Settings\Propietario\workspace\OwlGres

21-jul-2008 12:57:25 org.coode.owl.rdfxml.parser.OWLRDFConsumer endModel

INFO: Total number of triples: 618

21-jul-2008 12:57:25 org.coode.owl.rdfxml.parser.OWLRDFConsumer endModel

INFO: Loaded http://semantics.crl.ibm.com/univ-bench-dl.owl

FRAGMENT ERROR: No support for axiom OWLFunctionalObjectPropertyAxiom

On OWL Axiom: FunctionalObjectProperty(takesCourse)

The TBox is not compatible with DL-Lite

The TBos is not compatible with DL-Lite FR or DL-Lite A

DL-Lite F

DL-Lite FR

DL-Lite A

DL-Lite R


First target search4
First Target: Search

  • We verify for DL-Lite R:


First target search5
First Target: Search

  • We verify for DL-Lite R:

C:\Documents and Settings\Propietario\workspace\OwlGres

21-jul-2008 12:58:45 org.coode.owl.rdfxml.parser.OWLRDFConsumer endModel

INFO: Total number of triples: 619

21-jul-2008 12:58:45 org.coode.owl.rdfxml.parser.OWLRDFConsumer endModel

INFO: Loaded http://semantics.crl.ibm.com/univ-bench-dl.owl

The TBox is compatible with DL-Lite

OWL-Gres is based on DL-Lite R


First target search6
First Target: Search

  • But…

    • We have concept attributes…

  • IS-A for concept attribuites?

  • Range(Uc) IS-A Datatype NO

  • Person IS-A domain(Uc) assertion NO


First target conclusions
First Target: Conclusions

  • OWL-Gres is based on:

  • DL-Lite R

  • Concept attribuites

  • IS-A for concept attribuites


Second target preliminary notes
Second Target:Preliminary notes

edgeR-⊑Node

edgeR ⊑Node

edgeB-⊑Node

edgeB ⊑Node

NodeRB ⊑ edgeR

NodeRB ⊑edgeB

edgeB(a,a)

NodeRB(a)

ABOX

TBOX

q(x) ← y, z, w. edgeB(x,y)  edgeR(x,z)  edgeR(y,z)

{a}

  • Standard

2 types of semantic

q(x) ← y, z, w. edgeB(x,y)  edgeR(x,z)  edgeR(y,z)

  • Ground

{}

q(x,y,z) ← y, z, w. edgeB(x,y)  edgeR(x,z)  edgeR(y,z)

{}


Second target preliminary notes1
Second Target:Preliminary notes

q(x) ← hasSameHomeTownWith(x,y)  isMemberOf(y,z)  hasMember(z,t) isCrazyAbout(t,w)  isCrazyAbout(x,w)

Let’s consider the query 15:

isMemberOf

Y

Z

hasMember

The query is designed on purpose to establish if a reasoner is able to answer according to the standard conjunctive query semantic:

Quonto gives out 94 answers

OWLGres gives out 89 answers, like Racer, Pellet, etc..

hasSameHomeTownWith

T

isCrazyAbout

X

W

isCrazyAbout


Second target experiment conditions
Second Target:Experiment conditions

  • We have made two comparisons:

  • Without optimizations

  • Keep the reasoners near as much as possible from the optimizations point of view

  • With optimizations

  • What are they?


Second target experiment conditions1
Second Target:Experiment conditions

Optimizations


Second target experiment conditions2
Second Target:Experiment conditions

Semantic conjunctive query minimization

q(x) :- PeopleWithHobby(x), like(x,y)

PeopleWithHobby ⊑  like

Quonto

q(x) :- PeopleWithHobby(x)

Quonto

q(x) :- PeopleWithHobby(x), like(x,y)

 like⊑PeopleWithHobby

OWL-Gres

q(x) :- like(x,y)


Second target experiment conditions3
Second Target:Experiment conditions

Optimizations


Second target experiment conditions4
Second Target:Experiment conditions

Query containment

We considered:

q(x):- A(x)  q(x) :- A(x),B(x)

We can send to evaluate

q(x):- A(x)

ONLY in Quonto


Second target experiment conditions5
Second Target:Experiment conditions

Optimizations


Second target experiment conditions6
Second Target:Experiment conditions

In-expansion optimizations

q(x):-Man(x),Woman(x)

Consistent Ontology

answer {}

Man ⊑ ¬Woman

ONLY in Quonto


Second target experiment conditions7
Second Target:Experiment conditions

Optimizations


Second target experiment conditions8
Second Target:Experiment conditions

Auxiliar role optimization

  • For A ⊑R.C

Quonto and OWL-Gres

  • It’s introduced an auxiliar role

  • But has no membership assertion

  • We delete all querys with an auxiliar role


Second target experiment conditions9
Second Target:Experiment conditions

Optimizations


Second target experiment conditions10
Second Target:Experiment conditions

Selectivity optimization

ONLY in OWL-Gres

  • A concept, role or concept attribute has no membership assertions

  • We delete all the conjunctive queries with this element

  • It’s correct ?


Second target first comparison
Second Target: First Comparison


Second target first comparison1
Second Target:First Comparison


Second target first comparison2
Second Target:First Comparison


Second target first comparison3
Second Target:First Comparison


Second target quonto abox
Second Target: QuontoAbox

BaseballFanConcept:


Second target quonto abox1
Second Target: QuontoAbox

iscrazyabout Role:


Second target quonto abox2
Second Target: QuontoAbox

e-mail attribute of concept:


Second target owl gres abox
Second Target: OWL-GresAbox

TBOX_name:


Second target owl gres abox1
Second Target: OWL-GresAbox

TBOX_Concept_inclusion :


Second target owl gres abox2
Second Target: OWL-GresAbox

Individual_name :


Second target owl gres abox3
Second Target: OWL-GresAbox

Concept_assertion :


Second target owl gres abox4
Second Target: OWL-GresAbox

Object_Role_assertion:


Second target owl gres abox5
Second Target: OWL-GresAbox

Data_Role_assertion :


Second target second comparison
Second Target: Second Comparison


Second target second comparison1
Second Target: Second Comparison


Second target second comparison2
Second Target: Second Comparison


Second target second comparison3
Second Target: Second Comparison


Second target second comparison4
Second Target: Second Comparison


Conclusions
Conclusions

75 MB

55 MB


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