is mentioned by

Thm*  a,b:, P:({a..b}Prop). (i:{a..b}. P(i))  (Or i:{a..b}. P(i))

[exist_intseg_vs_iter_or]

In prior sections: core bool 1

Try larger context: DiscrMathExt IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html