1. Custom rules on subject verb agreement
David Ling

2. Contents Subject verb agreement: singular + plural_verb
A cat go to school
Subject verb agreement: plural + singular_verb
Cats goes to school
POSTag and OpenNLP Chunker
Control with Grammarly

3. Subject verb agreement: singular + plural_verb
POSTag
Singular noun (both from chunker and Postag)
Skip one optional adverb
Plural verb (both from chunker and postag)
Matches: cat(NN) go(VBZ)
3 exceptions added:
Does….singular noun
Modal verb…singular noun
And singular noun
Successful

4. Subject verb agreement: plural + singular_verb
Anti-pattern:
Except with preposition in front
example:
One of the cats
A word in the sentences
Plural Noun
Skip optional adverb
Singular verb
Successful
Fail when adj+plural noun. Why? Due to disambiguation rules for POSTags

5. Both of them are not correct 100% of the time (cat: VBZ)
Why fail?
In LanguageTool, you can obtain the part of speech by using POSTag and Chunker
POSTag:
Uses customizable rules with the embedded POS dictionary
Example rule: NNS/VBZ delete NNS if another NNS follows
It causes(NNS/VBZ) somethings(NNS).  It causes(VBZ) somethings(NNS).
Cats(NNS/VBZ) goes(NNS/VBZ) Cats(VBZ) goes(BBS/VBZ)
Chunker:
A parser in opennlp library, statistically trained
Group tokens into chunks and give part of the speech
B– begin of the chunk
I– intermediate of the chunk
E– End of the chunk
Both of them are not correct 100% of the time (cat: VBZ)

6. As the POSTag wrongly interpret the POS of “cats” as VBZ (singular verb)
the sequence doesn’t match the rule pattern
So I made another rule, add vbz to antipattern, use pos from chunker instead

7. Now it can recall adjective + plural noun
I think the rule is still not sophisticated
To be robust, more exceptions and testing are needed to reduce false alarms

8. And actually, there are existing verb agreement checking in the grammar.xml
The rule group contains 40 rules
Most of them focused on the beginning of the sentence, and only allow determinant but not numbers in front of the plural noun
Able to recognize: “The cats”, “Cats”, but not “The two cats”, “All cats”

9. Our LanguageTool
Grammarly
Suggest “an”

10. Suggest “they want”
Suggest “the”
Suggest “the whole”
Suggest “to”

11. Next possible rules: Plural or singular verb of compound subjects:
Except cases with “that” causes:
A dog [that loves its owners] deserves a reward.
Number + singular noun
There are three cats.

12. Number +singular noun

13. Marking process Machine Realize influent phases in a paragraph
Change/add/delete word
See if it is more fluent
Machine
Learn good language model
Low probability occurs at the influent phases (5 gram moving window).
Try change/add/delete inside the window to see if the probability raises (beam search)