Script from JKR's reading

[Neri]

No: HPFGUIDX 156832


> Nikkalmati: (not a mathematician so I am not sure the ramifications 
of  using 
> "implies")
> Let me try an example:
> Proposed statement:  If A is a doctor, B did not die.
> Assuming B did die, does that prove A is not a doctor?
> No

Neri:
Yes. 

> Nikkalmati:
> Of course, it is just as likely A is or is not a doctor.  We can't  
tell

Neri:
If A was a doctor then B didn't die. If it's also given that B *did* 
die then the unavoidable conclusion is that A can't be a doctor.

Neri