dialogue based meaning negotiation

Dialogue Based Meaning Negotiation

Gabrielle Santos, Valentina Tamma,Terry R. Payne & Floriana Grasso

University of Liverpool

[email protected]@liverpool.ac.uk

[email protected]@liverpool.ac.uk

Dialogue based Meaning NegotiationTerry Payne University of Liverpool

Alignment

Correspondence

Open Systems, Ontologies and Alignment

• Agents can assume different ontological models• Modelled implicitly, or explicitly by defining entities (classes, roles etc),

typically using some logical theory, i.e. an Ontology

• Alignment Systems align similar ontologies

2


Differences in Modelling• Different ways of modelling ontologies can generate

difficulties when trying to make an alignment.

3

Cow

Ontology 1

Farm Animal

Cow

Ontology 2

Herbivore

Soccer Football• Terminological heterogeneity:

• Different terms represent the same entity

• Structural heterogeneity:• The same concept is modelled differently from

one ontology to another. • Ontology 1: A Cow is a Farm Animal.• Ontology 2: A Cow is a Herbivore.


RDF/OWL Ontologies

• Concepts and properties are modelled as a graph• Concepts modelled as nodes

• Relationships between concepts are edges

• Triples represent a concept that has a relationship to another one • subject - predicate - object

4


RDF/OWL Ontologies




5


RDF/OWL Ontologies




6


Align Everything?

• Do we need everything to be aligned?• An agent may aggregate several ontologies for a variety of domains

• A task may be relevant to only a single fragment within an ontology

• Fragments of the ontological space may be confidential, or commercially sensitive.

• We focus only on a specific signature (set of ontological entities) relevant to a transaction.

7


Aligning with no prior knowledge ?

• Can two agents exchange partial knowledge to find a meaningful alignment?

• Existing approaches assume: • Full disclosure of knowledge to a 3rd party • Existence of existing alignment fragments • Knowledge of underlying grounds for correspondence generation

• What if there is no prior knowledge?8


Meaning-based Dialogue

• Dialogue fragment that…• Allows two agents to exchange knowledge about entities and

their relationships to agree upon a mutually acceptable final alignment.

• Disclose only those entities (T-Box) directly related to the correspondence

• Minimises the disclosure of redundant or irrelevant entities.9


Meaning-based Dialogue

• Explores a cognitive approach to reaching consensus over possible correspondences…• Agents identify possible concepts that may be

ontologically equivalent in their respective ontologies • Each then seeks further evidence over the locality of each

concept to verify if these are structurally similar. • Both agents have the opportunity to ask questions • Correspondences only accepted if both agents accept the

same underlying support

10


Meaning-based Dialogue• Inherently heuristic

• Need to balance exploration vs exploitation • Aim to find a pragmatic, if sub-optimal, solution that is fit for

purpose

• If all knowledge is disclosed, then could use 3rd party approach to find optimal solution

• If insufficient knowledge is disclosed, this could increase occurrence of false positives

• Depth of exploration is significant • Shallow structure similarity can fail due to modelling differences • However, deeper structural similarities hay have less relevance

11


Roadmap• Work to date has developed

• Cognitive framework that underpins the dialogue

• Dialogue fragment targeted at allowing two agents to agree on a single correspondence

• Protocol / Finite State Machine describing the permissible moves during the dialogue

• Practical reasoning approach to determine what moves to make at each state - this however is dependent on the objective function

• Work presented here covers• Underlying cognitive model

• State machine and moves

12

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept


Cognitive Approach

13

Open

Propose

Close

Confirm

Agent initiates the dialogue • Identify the name of the entity to be aligned. • Interlocutor can chose to offer a candidate

corresponding entity, or reject the dialogue

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept


Propose

14

Open

Propose

Close

Confirm

Allows agent to gather supporting evidence in favour of a correspondence

• Asks for triples representing the entities locality • Attempts to match this to its own triples

If sufficient support found, then it can assert a correspondence

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept


Confirm

15

Open

Propose

Close

Confirm

Interlocutor verifies the support for the correspondence

• Can accept the correspondence • May ascertain its own evidence to augment the

support (i.e returning to the propose phase)

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept


Close

16

Open

Propose

Close

ConfirmAlice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Dialogue fragment terminates if • Both agents accept the correspondence • No support can be found that is acceptable to

both agents


Roadmap (cont)

• We assume (for now)…1. Candidate concepts will be lexically similar

• Lexical Similarity Metrics exist - black box approach

2. Structural similarity can be found on partial ontological fragments • Such metrics exist (such as similarity flooding), but unclear how to

determine depth of exploration

3. Agents will have different knowledge bases, and possibly different similarity metrics • What holds for one agent, cannot be guaranteed to hold for the other

17


Roadmap (cont)• We assume (for now)…

4. Concept relationships (triples) will be disclosed in order of significance • Mechanism to establish this is subject of other work

5. Threshold is a function of the size of the support, and non-linear • If we assume that the most significant triple is

disclosed, but is not sufficiently convincing, then subsequent evidence may strengthen the support, but not increase the quantitative mean

• A function has been selected that reduces the threshold asymptotically as the number of triple pairs (x) increases

18

"(x) = 12(x+1) + 0.5

0.5

0.6

0.7

0.8

0.9

1

0 5 10 15 20

f(x)


Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Dialogue Moves: initiate & fail

• These moves are used to initiate or close (through failure) the dialogue• <a, initiate, e, nil, nil>

• Agent a starts the dialogue fragment by offering the name of the source entity e

• <a, fail, e, nil, nil> • Agent a cannot find a candidate destination entity to map to the source

entity e

19

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept


Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Dialogue Moves: propose & rejectC

• These moves are used to propose or reject a possible correspondence between entities e and e’• <a, propose, e, e’, nil>

• Agent a suggests a candidate destination entity e’ as one that matches the source entity e. However, no support yet exists to assert this as a correspondence.

• <a, rejectC, e, e’, nil> • Agent a has failed to find any convincing evidence to accept a

candidate correspondence between e and e’.

20

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept


Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Dialogue Moves: justify & testify

• These moves are used to propose or reject a possible correspondence between entities e and e’• <a, justify, e, e’, nil>

• Agent a requests a new triple to support the candidate correspondence.

• <a, testify, e, e’, 𝜛> • Agent a responds to a justify request by providing a (previously

undisclosed) triple 𝜛 based on the locality of the entity (e or e’) in its ontology.

21

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept


Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Dialogue Moves: assert & rejectS

• These moves are used to assert or reject a possible correspondence based on supporting evidence• <a, assert, e, e’, 𝛼>

• Agent a asserts the argument 𝛼 for a candidate correspondence given a subset of triples believed to be matching (from agent a’s perspective).

• <a, rejectS, e, e’, 𝛼> • Agent a rejects the argument 𝛼 as the support was not believed

convincing (from that agent’s perspective).

22

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

An argument 𝝰 is a tuple (S, c) where:S = set of matching pairs of triples c = candidate correspondence

Move Locution

1 hAlice, initiate, d,nil ,nili2 hBob, propose, d, w,nili3 hAlice, justify , d, w,nili4 hBob, testify , d, w, hw, t, yii5 hAlice, justify , d, w,nili6 hBob, testify , d, w, hw, r, zii7 hAlice, assert, d, w, ({(hd, l, gi, hw, t, yi), (hd, k, ei, hw, r, zi)}, hd,w,⌘i)i8 hBob, justify , d, w,nili9 hAlice, testify , d, w, hd,m, fii10 hBob, assert, d, w, ({(hw, t, yi, hd, l, gi), (hw, r, zi, hd, k, ei), (hw, s, xi, hd,m, fi)},

hd,w,⌘i)i11 hAlice, accept, d, w, hd,w,⌘i)


Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Dialogue Moves: accept

• This move confirms the acceptability of the correspondence• <a, accept, e, e’, 𝛼>

• Agent a accepts the support, and hence argument 𝛼 for a candidate correspondence between e and e’.

23

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept

Alice3A

Bob2B

Alice1A

Bob4B

Alice6A

Alice8A

Bob5B

Bob7B

fail

initiate

rejectC

propose

rejectC

justify

testify

justify

justify

assert

rejectS

justify

testify

assertrejectS

accept

accept


Example Dialogue

24

Alice’s PrivateKnowledge

As the support is below threshold (from Alice’s perspective), she requests further evidence to support the candidate correspondence between d and w.

Commitment Store CS (Public Knowledge)

Bob’s Private KnowledgeOntology

d

e fw

y

z

t

Alice's

Ontology Bob's

Ontology

k

l

m

xg

s

r

n h

Ontology

d

e fw

y

z

t

Alice's

Ontology Bob's

Ontology

k

l

m

xg

s

r

n h

Alice’s $ Bob’s $ �Alices

hd, l, gi hw, t, yi 0.66

Gamma Store Γ Gamma Store Γ

Move Locution



Move Locution



S = {(hd, l, gi, hw, t, yi)}�̄Alices (S) = 0.66

"(|S|) = 0.75 ✘

"(x) = 12(x+1) + 0.5

0.5

0.6

0.7

0.8

0.9

1

0 5 10 15 20

f(x)

Dialogue based Meaning NegotiationTerry Payne University of Liverpool 25

Commitment Store CS (Public Knowledge)Move Locution



Move Locution



Bob responds with another triple in the locality of the concept w. Alice now has sufficient support to assert the correspondence.

Gamma Store Γ

Ontology

d

e fw

y

z

t

Alice's

Ontology Bob's

Ontology

k

l

m

xg

s

r

n h


hd, l, gi hw, t, yi 0.66hd, k, ei hw, r, zi 0.70

S = {(hd, l, gi, hw, t, yi),(hd, k, ei, hw, r, zi)}

�̄Alices (S) = 0.68

"(|S|) = 0.6̇ ✔


Gamma Store Γ

Ontology

d

e fw

y

z

t

Alice's

Ontology Bob's

Ontology

k

l

m

xg

s

r

n h

Bob’s Private Knowledge





Move Locution



Alice makes the assertion; however, from Bob’s perspective, the support is below threshold.

Gamma Store ΓGamma Store Γ

Ontology

d

e fw

y

z

t

Alice's

Ontology Bob's

Ontology

k

l

m

xg

s

r

n h

Ontology

d

e fw

y

z

t

Alice's

Ontology Bob's

Ontology

k

l

m

xg

s

r

n h



Alice’s $ Bob’s $ �Bob

s



�̄Alices (S) = 0.68

"(|S|) = 0.6̇ ✔ ✘


�̄Bob

s (S) = 0.64"(|S|) = 0.6̇




Gamma Store ΓGamma Store Γ

27




Move Locution



Ontology

d

e fw

y

z

t

Alice's

Ontology Bob's

Ontology

k

l

m

xg

s

r

n h

Ontology

d

e fw

y

z

t

Alice's

Ontology Bob's

Ontology

k

l

m

xg

s

r

n h



Alice’s $ Bob’s $ �Bob

s



�̄Alices (S) = 0.68

"(|S|) = 0.6̇ ✔ ✘


�̄Bob

s (S) = 0.64"(|S|) = 0.6̇

It is now Bob’s turn to request additional evidence from Alice to support the candidate correspondence between d and w.







Move Locution





Ontology

d

e fw

y

z

t

Alice's

Ontology Bob's

Ontology

k

l

m

xg

s

r

n h

Ontology

d

e fw

y

z

t

Alice's

Ontology Bob's

Ontology

k

l

m

xg

s

r

n h

Gamma Store Γ Gamma Store Γ

✔

Alice responds with another triple in the locality of the concept d. Both Bob and Alice have sufficient support to assert and accept the correspondence.

Alice’s $ Bob’s $ �

Bob

s

hd, l, gi hw, t, yi 0.60hd, k, ei hw, r, zi 0.68hd,m, fi hw, s, xi 0.61

S = {(hd, l, gi, hw, t, yi),(hd, k, ei, hw, r, zi),(hd,m, fi, hw, s, xi)}

�̄

Bob

s (S) = 0.63"(|S|) = 0.625 ✔


�̄Alices (S) = 0.68

"(|S|) = 0.6̇




Ongoing work• Formally defining / validating the dialogue

• Currently only the performatives / moves have been defined. • The decision-making process at each step of the protocol is being defined

for possible objective functions • Minimising disclosure • Minimising support etc

• Determining similarity metrics• Several approaches to determining:

• lexical similarity - simple !!! • structural similarity - not so easy…

• Ranking triples for disclosure is more tricky (objective-function dependent)

29


Ongoing work (cont)• Expanding the dialogue beyond

single correspondences• Current fragment handles exchange of

triples pertaining to the locality of one candidate correspondence (i.e. singleton signature).

• Need to extend this for signatures for multiple entities.

• Include ability to accept existing, established correspondences.

• Resolve ambiguous alignments (re-negotiate if multiple candidates are possible)

30

publication article author

submittedPaper reviewedPaper paper editor

A Dialectical Approach to Selectively Reusing Ontological CorrespondencesValentina Tamma University of Liverpool

Questions

31

For other papers on this and our other related work:

http://www.csc.liv.ac.uk/~trp/Knowledge-Based-Agents.html

http://www.csc.liv.ac.uk/~trp/Knowledge-Based-Agents.html

dialogue based meaning negotiation

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