This applies to rates using [p en/per] or [p en/by] to specify a unit, or atemporal [p en/for] + _each_/_every_ indicating a regular correspondence:

- [ex 001 "The cost is $10 [p en/per SetIteration] item."]

- [ex 002 "A fuel efficiency of 40 miles [p en/per SetIteration] gallon (of gas)"]

- [ex 003 "Pizza is sold [p en/by SetIteration] the slice."]

- [ex 004 "They charge [p en/by SetIteration] the hour."]

It also applies to expressions that denote a generalization over a set:

- [ex 005 "Pets [p en/in_general SetIteration] tend to trigger my allergies."]

- [ex 006 "Supposedly, [p en/on_average SetIteration] we consume a gallon of milk every day."]

Contrast [ss Frequency], which describes _how often_ an _event_ occurs.

## NPN Construction

[ss SetIteration] applies to the preposition linking two nominals (often the same noun) when the combination carries a meaning of iteration or regular correspondence. This applies whether the nouns are temporal or atemporal:

- [ex 007 "day [p en/to SetIteration] day tasks"]
- [ex 008 "day [p en/by SetIteration] day"]
- [ex 009 "day [p en/after SetIteration] day"]
- [ex 010 "We interviewed candidate [p en/after SetIteration] disappointing candidate."]
- [ex 011 "We’ll match your contribution dollar [p en/for SetIteration] dollar."]
- [ex 012 "They went house [p en/to SetIteration] house in search of the fugitive."]

These exemplify what is known as the NPN Construction: it is syntactically idiosyncratic, as the preposition and second noun cannot necessarily be omit- ted (_*We’ll match your contribution dollar._) ([Jackendoff, 2008](/bib/jackendoff_2008)).[^1]

Not all instances of the construction have an iterative meaning, however:

- [ex 013 "morning [p en/to Duration--EndTime] night talks"] ([ss Duration--EndTime])
- [ex 014 "wall [p en/to Extent--Goal] wall carpeting"] ([ss Extent--Goal])

Note that in ([exref 007 SetIteration]–[exref 014 SetIteration]), the scene role technically represents the semantic output of the whole construction. In [exref 013 SetIteration]–[exref 014 SetIteration], the function is different from the scene role, focusing on the preposition as a marker of the second nominal.

*[ss SetIteration] replaces an older and narrower supersense, [ss RateUnit].*

[^1]: Only a few prepositions occur productively in this construction. In the interest of simplicity, we refrain from attempting to assign a separate function (such as [ss Goal] for [p en/to] or [ss Time] for [p en/after]) that may explain why certain prepositions participate in the construction with a certain meaning.

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