I am trying to make a regex pattern for a Watson Assistant Entity that detects dates similar to those in bold:

* date 25/2/2020 30/2/2020
* date /25/2 **30/2** of
* date **18/02** of
* date 12/12/ of
* date 12/12/
* date **12/12**

I have used the following expression to do it:

```
( \b(?:3[01]|[12][0-9]|0?[1-9])([\-/.])(1[1-2]|0?[1-9])(?![\-/.])\b )

```

This expression works well, the problem is that the pattern comparison engine that is used in Watson, has syntax limitations.

Entity patterns cannot contain:

* Positive repetitions (for example, x\*+)
* Previous references (for example, \g1)
* Conditional branches (for example, (? (Cond) true))

At this point, I cannot use (?![-/.]) to avoid dates like '25/02/2020'.

How can I do it?

Thanks in advance,