Algorithm Design

I'm collecting important sentences from linguistics to parse examples to look at for algorithm design in machine reading.

“The girl whose car is blocking my view of the tree that I planted last year is my friend.”

This sentence is from a psycholinguistics article [1] and illustrates recursion or “the use of relative pronouns to refer back to earlier parts of a sentence.”

1) IsFriendOf(girl,I)
2) Possesses(girl,car)
3) Obscuring(car,ViewOf(I,tree))
4) On(Planted(I,tree),last year)

Each of these is a simpler sentence. The predicates' arguments are bound identically which shows the use of URI or integers as opposed to strings as the goal is to be able to place these four into a knowledgebase where they can be used with other knowledge and to retrieve them and reassemble the sentence (sentence aggregation [2]) or sentences as needed.

Simulating the process of accumulating these predicates when processing the sentence in left to right order, or sequentially:

P1(girl, A2)

P1(girl, A2)
Possesses(girl,A3)

P1(girl, A2)
Possesses(girl,car)

P1(girl, A2)
Possesses(girl,car)
Obscuring(car,A4)

P1(girl, A2)
Possesses(girl,car)
Obscuring(car,ViewOf(I,A5))

P1(girl, A2)
Possesses(girl,car)
Obscuring(car,ViewOf(I,tree))

P1(girl, A2)
Possesses(girl,car)
Obscuring(car,ViewOf(I,tree))
P2(I,tree)

P1(girl, A2)
Possesses(girl,car)
Obscuring(car,ViewOf(I,tree))
Planted(I,tree)

P1(girl, A2)
Possesses(girl,car)
Obscuring(car,ViewOf(I,tree))
On(Planted(I,tree),last year)

IsFriendOf(girl, I)
Possesses(girl,car)
Obscuring(car,ViewOf(I,tree))
On(Planted(I,tree),last year)

Another pair of important sentences are:
1) “Fred saw the plane flying over Zurich.”
2) “Fred saw the mountains flying over Zurich.”

1a) Saw(fred,FlyingOver(plane,zurich))
2) While(Saw(fred,mountains),FlyingOver(fred,zurich))

P1(fred,A2)	P1(fred,A2)
Saw(fred,A2)	Saw(fred,A2)
Saw(fred,P2(plane,A3))	Saw(fred,mountains)
Saw(fred,FlyingOver(plane,A3))	While(Saw(fred,mountains),FlyingOver(fred,A3))
Saw(fred,FlyingOver(plane,zurich))	While(Saw(fred,mountains),FlyingOver(fred,zurich))

Looking at the bold line, and assuming a sequential processing, it appears that both hypotheses should be kept by an algorithm at that step. These sentences are an argument for knowledge-based processing and lexical data. It does appear that properties of “mountains” and “plane” can distinguish between hypothesized semantic parses. However, a word like “birds” could be in either parse structure or both simultaneously, depending on the context, for example seeing birds from a plane. Theoretically, knowledge-based, statistical and context-based methodologies can help discern between parse candidates.

Another possible representation of those sentences:
1b) While(Saw(fred,plane), FlyingOver(plane,zurich))
2) While(Saw(fred,mountains),FlyingOver(fred,zurich))

This representation makes clear that the difference is in binding the first argument of FlyingOver. The side by side processing of these two would otherwise be equivalent. I'll have to look at more sentences to determine whether 1a or 1b is more useful or if they are equivalent via a rule system. The representation is important in discerning the algorithm. I'm hopeful a corpus will aid in this area.

The sequential processing hypothesis is based on the proof of concept manner in which people read sequentially, however machines need not process text in the same manner. Additionally, even in the sequential processing hypothesis there are possiblities, for example, the text processor could be one or more words ahead of the predicate generator.

Other hypotheses include structural processing where the semantic tree is generated in a top-down or bottom-up manner based on data, patterns and substructural patterns collected and discerned from a corpus. This information can help determine a parse structure based on the fact that one usage of language resulting in one parse structure is extremely rare and the other commonplace.

[1] Psycholinguistics, Wikipedia
[2] Natural Language Generation, Wikipedia