The omission test is a variant of the substitution test, viz. it is substitution by zero. If the dependent in the dative of a is replaced by an accusative form, the result in #b becomes ungrammatical. Which shows that this verb takes an indirect object.
| . | a. | Linda hilft mir. |
| German | Linda helps me. | |
| b. | *Linda hilft mich. | |
| – | ||
| c. | Linda hilft. | |
| Linda helps. | ||
If, instead, the dependent is replaced by zero, i.e. it is omitted, as in #c, the result is grammatical. Which shows that this indirect object is optional.
In coding a situation where an animate being is affected on one of its body parts, German sometimes has an alternative of two case patterns:
| . | a. | Linda trat mir auf den Fuß. |
| b. | Linda trat mich auf den Fuß. | |
| German | Linda trod on my foot. | |
The person affected is in the dative in #a, but in the accusative in #b. Since the two versions are essentially synonyomous, this appears superficially to be an inconsequential free variation in the case of some verbal dependent. The omission test, however, reveals that two different constructions are involved:
| . | a. | *Linda trat mir. |
| b. | Linda trat mich. | |
| German | Linda kicked me. | |
This suggests that the accusative constituent in the #b version may be a direct object, while the dative constituent in the #a version probably is not an indirect object, because then it would be inexplicable that the prepositional phrase is inomissible.
Applying the omission test, instead, to the two variant expressions of , we get .
| . | Linda trat auf den Fuß. |
| German | Linda trod on the foot. |
This is semantically odd,1 but grammatical. The semantic oddity disappears if Fuß is replaced by Teppich ‘carpet’. This shows that .b illustrates one valency frame of treten ‘trod, kick’, and exemplifies another one.
If this is so, then .a must be an expanded variant of , featuring a dativus incommodi which triggers the inference of a possessive relation: mir in .a is a so-called external possessor.
Result of the omission test: Far from featuring case variation in a given verb dependent, represents two entirely different constructions:
- .a exemplifies a valency frame of treten which includes a directional complement. If this is a body part term, its possessor is commonly coded as a dativus incommodi.
- .b exemplifies a valency fram of treten which includes a direct object. This is compatible with an optional directional adjunct.
1 It would normally presuppose that the foot is a detached body part.