What is ambiguity in this example?

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The instructor for my class assigned homework that is not covered in both the class and the textbook. As a result I found this problem and cannot find anyway to solve it. Can someone link some reading materials or explain the concept I'm missing please? I don't know what I'm looking at here.

Enter T or F depending on whether the formula is ambiguous (T) or not (F). (You must enter T or F -- True (true) and False (false) will not work.)

  1. p∨(q∨r)

  2. p∧q∧r

  3. p
  4. p∨q
  5. p∧q∨(q∧r)

This is homework, so I'm not asking anyone to do it for me per se, but an example would help me (and my equally confused classmates) out greatly!

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I am not sure, but I imagine in that case "ambiguous" is understood as "can be interpreted as different nonequivalent formulas by adding parentheses". For instance, if I understand correctly, $p \wedge q \wedge r$ is not ambiguous, because the two ways to understand it, namely $p \wedge (q \wedge r)$ and $(p \wedge q) \wedge r$, are equivalent (they are either both true or both false, depending on whether $p$, $q$, and $r$ are).

The last one, however, would be ambiguous, because it can be understood either as $(p \wedge q) \vee (q \wedge r)$ or as $p \wedge (q \vee (q \wedge r))$, which are not equivalent. Indeed, if $p$ is false but $q$ and $r$ are true, the first one is true while the second one is false.