Learn English – “Let A be a set, [let] B [be] a group”

grammaticalitymathematicsparallelismverbs

Math proves often start with "let". For example:

Let A be a set.

This is easy. But what about introducing several things in that manner?

  1. Let A be a set, B be a group, and C be a number.
  2. Let A be a set, let B be a group, and let C be a number.
  3. Let A be a set, B be a group, and let C be a number.
  4. Let A be a set, B a group, and C a number.

Which is the most correct one?

Best Answer

As Benjamin Wade comments, 4) is the most concise. 1) and 2) are long-winded but consistent in their presentation of the premises, and 3) is inconsistent (and hence has the least desirable wording).

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