Description: Define predicate that
determines if some class 𝐴 is a function.
Definition 10.1 of [Quine] p. 65. For
example, the expression
Fun cos is true once we define cosine (df-cos 15424). This is not the
same as defining a specific function's mapping, which is typically done
using the format of cmpt 5146 with the maps-to notation (see df-mpt 5147 and
df-mpo 7161). Contrast this predicate with the
predicates to determine if
some class is a function with a given domain (df-fn 6358), a function
with a given domain and codomain (df-f 6359), a one-to-one function
(df-f1 6360), an onto function (df-fo 6361), or a one-to-one onto function
(df-f1o 6362). For alternate definitions, see dffun2 6365, dffun3 6366,
dffun4 6367, dffun5 6368, dffun6 6370, dffun7 6382, dffun8 6383, and dffun9 6384.
(Contributed by NM, 1-Aug-1994.) |