On Jan 24, 12:12 pm, "Peter Percival" <peterxperci...@hotmail.com> wrote: > Writing <...> for an ordered n-tuple; is the second projection of <x,y,z> > y or <y>? >

The second projection is a function from X x Y x Z -> Y taking <x,y,z> |-> y so the second projection of your particular triple <x,y,z> is y