For Each Partial Function, Determine Its Domain, Codomain, Domain of Definition

Short Answer

for each partial function, determine its domain, codomain, domain of definition, set of values for which it is undefined or if it is a total function:
- $$f : \mathbf { Z } \times \mathbf { Z } \rightarrow \mathbf { Z } , \text { where } f ( m , n ) = m - n \text { if } m > n$$