set "baseuri" "cic:/matita/tests/fold".
alias id "nat" = "cic:/Coq/Init/Datatypes/nat.ind#xpointer(1/1)".
alias num (instance 0) = "natural number".
-alias symbol "eq" (instance 0) = "leibnitz's equality".
-alias symbol "plus" (instance 0) = "natural plus".
+alias symbol "eq" (instance 0) = "Coq's leibnitz's equality".
+alias symbol "plus" (instance 0) = "Coq's natural plus".
theorem t: \forall x:nat. 0+x=x.
intro.
simplify in match (0+x) in \vdash (? ? % ?).