Picking Reference Events from Tense Trees: A Formal, Implementable Theory of English Tense-Aspect Semantics

What it is about

The paper turns English tense and aspect into explicit relations between episodes (events and situations) in a formal episodic logic. Each sentence's logical form is first built compositionally, with separate past, present, perfect and future operators. A "tense tree" then serves as context. Each node has a past, a perfect and a future branch, and the focus moves as the operators are met. The rules for present, past, future, perfect and that-clauses rewrite the indexical form into episode variables, with relations such as "before", "orients" and "at-about", and they store the new episode at the focal node. Later inference discharges the "context-charged" relations, for example a default that the next event follows its reference point. The rules are implemented in Common Lisp. The example traces (for instance a sequence of past-tense sentences about John and Mary) come out as the intuitive order, and the example sentences run in about a tenth of a second on a 1990 workstation. The paper reports no accuracy measure.

Ideas

• I1. Use a tense tree as the deterministic store of event order in world/src/narr.rs: each event gets a node, and the order a text implies can be read off and checked. Measure it against hand-coded orders from the school lessons.
• I2. Implement the two perfect readings (perf1 and perf2) and test the paper's contrast: "John has left yesterday" is out, "John had left the day before" is in. Use these as grammar tests for 13. Verbs.
• I3. Store a "why" string with each ordering: the rule that placed the event and the orienting event it used. This is the explanation Mova asks for.
• I4. Negative control: scramble the sentence order of a passage. A tree-based ordering must change, and a rule that ignores tense must not.

For Mova

The chapter is 13. Verbs (with 14. Irregular verbs for forms). The code is en/src/morph.rs (tense forms), world/src/narr.rs and world/src/events.rs. The measure is event-order accuracy on a fixed set of passages with gold orders, run twice, with the scrambled-order control above.

Cite

The paper itself, not this card. BibTeX from the library's record of the work.

@inproceedings{schubert1990picking,
  title = {{Picking Reference Events from Tense Trees: A Formal, Implementable Theory of English Tense-Aspect Semantics}},
  author = {Schubert, Lenhart K. and Hwang, Chung Hee},
  booktitle = {Speech and Natural Language: Proceedings of a Workshop Held at Hidden Valley, Pennsylvania, June 24-27, 1990},
  year = {1990},
  url = {https://aclanthology.org/H90-1008/}
}

References

19 references, 0 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

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