This web demo accompanies the paper:
Steels, L. and P. Van Eecke (2016). Insight grammar learning using pro- and anti-unification. Under Review.
Explanations on how to use this demo are here.
WD-3. Search space comprehension.
WD-4. Search space production.
WD-5. Handing agreement failure using variable decoupling.
WD-6. Handling word order deviation using variable decoupling.
WD-7. Handling mismatch in feature values using Value Relaxation
WD-8. Unit and feature or predicate deletion
WD-9. Consolidating a new word order using pro-unification
WD-10. Consolidating a simpler construction using pro-unification
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Click on a box to see details.
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The same variable occurs more than once in the pattern but corresponds to different values in the source. In this case, this variable can be split into different variables for each case.
The utterance `un petit fille' (a small girl) cannot be parsed due to a conflict in gender between article, adjective, noun.
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The NP construction has not applied and therefore the meaning supplied by individual words is not properly connected.
Resulting anti-unified construction:
Note how this generalization has different variables for the gender feature between the noun, and the article and adjective.
When we apply this generalized construction we get a connected interpretable meaning, which implies that the generalized construction could Match with the transient structure and Merge. Here is the final transient structure
And its derived meaning:
The utterance `un dīner formidable' (a formidable dinner) cannot be parsed due to deviant constituent order according to the current grammar (NP-CXN).
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The NP construction has not applied and therefore the meaning supplied by individual words is not properly connected.
Note how this generalization has different variables within the meets constraints.
When we apply this generalized construction we get a correct interpretable meaning, which implies that the generalized construction could Match with the transient structure and Merge. Here is the final transient structure:
And the derived meaning:
Value-relaxation means that there is a different value for a particular feature in the pattern and in the source. It is resolved by assuming that the value is a variable in the more general pattern.
English Grammar fragment used in this example:
`The children' is comprehended correctly, but processing `many children' gets stuck.
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The NP-cxn could not apply because the feature because the determiner ?det expects an article as lex-cat. We now anti-unify the NP-cxn with the final transient structure. It creates a new construction where the lex-cat feature is variable.
Anti-unified NP-cxn:
Transient structure after applicaton of the anti-unified construction:
And the derived meaning:
The NP-cxn cannot apply to the utterance 'une fille', as it needs an article, an adjective and a noun.
Original construction:
Transient Structure:
By anti-unifying the construction with the transient structure, we get a new construction which only requires two units. Note that the ordering constraints are generalised to an unbound variable.
Anti-unified construction:
The word order of the input utterance `un dīner formidable' conflicts with the word order specified in the NP-cxn. Anti-unification helps to arrive at an interpretation and then pro-unification is used to consolidate this repair.
Original Construction:
Transient Structure:
We will now anti-unify the construction with the transient structure. The word order (meets constraints) or now generalised to unbound variables.
Anti-unified Construction:
We will now use pro-unification to constrain the anti-unified construction towards the transient structure. We can see in the meets constraints that the word order is learned.
Pro-unified Construction:
Application Result of the pro-unified construction on the transient structure:
Demonstration of the use of the pro-unified construction in formulation:
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Original construction:
Transient Structure:
By anti-unifying the construction with the transient structure, we get a new construction which only requires two units. Note that the ordering constraints are generalised to an unbound variable.
Anti-unified construction:
Now, we pro-unify the anti-unified np-cxn with the transient structure. The ordering constraints that are learned in this construction is that the article should immediately preceed the noun.
Pro-unified construction:
Result:
The learned construction can now also be used in formulation.
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We carried out experiments with three sets of French utterances: (i) utterances that can be parsed by the initial grammar, (ii) utterances that are novel but grammatical in French and can be learned, and (iii) non-grammatical utterances which should not be parsable. Below are some examples of the constructions generalized through anti-unification and then pro-unified or not.
For the experiment reported in the paper, the following three anti-unified and pro-unified NP-constructions were generated:
An anti-unified NP-cxn with relaxed gender constraints to accommodate for the sentence 'une petite fille'.'
An anti-unified NP-cxn with relaxed form constraints and relaxed gender constraints. It was made for the utterance 'une semaine bouleversante'
An anti-unified NP-cxn for NPs without adjective. It does not constrain the the gender of article and noun to be equal, nor to be adjacent. It was made for the utterance 'une feuille'
A pro-unified NP-cxn for noun phrases in which article, ajective and noun have the same gender and occur in this order, e.g. la petite fille.
A pro-unified NP-cxn for noun phrases in which article, noun and adjective have the same gender and occur in this order, e.g. une semaine bouleversante
A pro-unified NP-cxn for NPs without adjective. Article and noun should have the same gender. It was made for the utterance 'une feuille'