Should I put an indefinite article in front?

Question

There are two main approaches to extracting information from less structured or even free text web pages: classification-based approach and sequential labeling-based approach.

It is from my thesis. A revision suggestion from the committee is that I should add an indefinite article before "classification". In other words, change the whole sentence to:

There are two main approaches to extracting information from less structured or even free text web pages: a classification-based approach and a sequential labeling-based approach.

The revised version would sound a little strange to my ears. Is it correct?

Answer 1

My understanding is that determiners (an article is a determiner) can be omitted when the noun is

1. a proper noun (Jim is speaking.)
2. a plural noun (Approaches to consider are...)
3. a non-count noun (Dessert is being served.)

So you might try substituting plural nouns as in this example:

There are two types of approaches to extracting information from less structured or even free text web pages: classification-based approaches and sequential labeling-based approaches.

Otherwise, with singular nouns, I would say your advisors are right. (By the way, advisors are always right, even when they are wrong!)

You could also omit the noun completely, as in this example:

There are two approaches to extracting information from less structured or even free text web pages: classification-based and sequential labeling-based.

This sidesteps the need for a determiner altogether.