Let's say I have this sentence:

This process uses [summation] and produces z.

Should it be written like this:

This process uses w, x and y and produces z.

Or like this?

This process uses w, x, y and produces z.

  • How about this one: This process uses w, x, and y to produce z. That would eliminate the awkward and-and construct that troubles you.
    – J.R.
    Commented Nov 4, 2013 at 11:26

2 Answers 2


The latter example doesn't make sense:

This process uses w, x, y[,] and produces z.

This looks like it contains a four-element list, but it can't; the reader will quickly see that produces z can't possibly combine with this process uses, so they'll instead interpret "w, x, y" as an asyndetic three-element list. ("Asyndetic" means lacking an overt coordinator such as and.)

Unfortunately, in this context asyndetic coordination is strange, and it may confuse some readers. The combination of two ands is better:

This process uses w, x[,] and y and produces z.

The first and signals to the reader that the following element y completes the list. This allows the reader to unambiguously interpret and produces z as separate from the list.

(I've placed the optional serial comma in square brackets. It doesn't make a difference here.)

Of course, as J.R. and gelolopez point out, you don't have to write either of these sentences. You can avoid a perceived problem by writing a different sentence, if you like.


If you use all w,x,and y to produce z, some standards dictate that you should use

...uses w,x,and y, and produces z.

This is called serial comma or an Oxford Comma.

But in order to avoid any confusion, I suggest you write your sentence like this:

This process uses w,x, and y, which produces z.

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