FTA Sections DiscrMathExt Doc
IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html
Def  a ~ b == a | b & b | a

is mentioned

In prior sections: num thy 1

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

FTA Sections DiscrMathExt Doc