FOM: Re: First-order logic -- a query

[Kanovei]

>From: "Michael Thayer" <mthayer at ix.netcom.com>
>Date: Thu, 15 Jan 1998 10:37:46 -0600

>I ask why use of Z or ZF or ZFC instead of NF, NFU,
>NFC or the Church systems?

I personally use ZFC, as the background system, 
in my mathematical research work 
because it provides me with reliable instrumentarium 
to deal with mathematical objects. Any known  
alternative does not stay contest with ZFC. 

I mean I can see myself studying e.g. topoi -- as 
interesting objects in the ZFC set world, but not 
as the background for mathematics. 

But it is clear that there are big branches in 
mathematics which are perhaps in no need in any 
sort of set theoretic or any other background.

Vladimir Kanovei