Function application The power of type theories is in specifying how terms may be combined by way of inference rules. Type theories which have functions also have the inference rule of function application: if is a term of type , and is a term of type , then the application of to , often written , has type . For example, if one knows the type notations , , and , then the following type notations can be deduced from function application.
function application the power of type theories is in specifying how terms may be combined by way of inference rules type theories which have functions also have the inference rule of function application if is a term of type  and is a term of type  then the application of to  often written  has type  for example if one knows the type notations   and  then the following type notations can be deduced from function application