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