alias id "nat" = "cic:/Coq/Init/Datatypes/nat.ind#xpointer(1/1)".
alias symbol "eq" (instance 0) = "Coq's leibnitz's equality".
alias symbol "plus" (instance 0) = "Coq's natural plus".
-alias num (instance 0) = "natural number".
+alias num (instance 0) = "Coq natural number".
alias symbol "times" (instance 0) = "Coq's natural times".
theorem para1: