Gapping

Gapping is an example of a deletion rule. It only applies in coordinate clauses and is very common in conversation. It is similar to verb phrase deletion, but is also different in certain respects.

Like verb phrase deletion, gapping operates only under certain conditions. Deletion is not possible in all circumstances. Let us examine differences between the two.

Verb phrase deletion can operate in both subordinate and coordinate clauses. This can be exemplified by the sentences Joseph works too much even though he shouldn't and Joseph works too much, but he shouldn't. In the examples, the deleted verb phrase follows the antecedent, but it can also precede it. The following sentences are also possible: Even though he shoudn't, Joseph works too much and He shouldn't, but Joseph works too much. In the latter sentence, the conjunction remains between the two clauses.

With gapping, however, the rule applies only to coordinate clauses, not to subordinate clauses. The following sentence is ungrammatical: *Diana studied chemistry even though Carol physics. The following sentence is fine: Diana studied chemistry and Carol physics. 

Unlike with verb phrase deletion, the gapping rule requires that the gap follow but never precede the antecedent. The sentence *Carol physics, and Diana studied chemistry is ungrammatical. In this case, the first clause of the sentence must include the verb.

Deletion rules are very common in language. One type of deletion rule is gapping. However, gapping does not apply in all circumstances, It only applies to coordinate clauses, and the gap must follow the antecedent.