Where do you want to do the condition, on an aggregate?
If so you have built-in functions to give you the current date. As CurrDateTime() and CurrDate()

With that, it will be possible to do that verification in an aggregate.
You add a filter and you add the condition

dateofbirth<CurrDateTime() and dateofdeath>dataofbirth
The CurrDate is to compare with variables or attributes with data type date and CurrDateTime is to compare with attributes with data type date time.
You can see the descriptions of each function.
Kind Regards,
Márcio