| 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 14845). This is not the
same as defining a specific function's mapping, which is typically done
using the format of cmpt 4762 with the maps-to notation (see df-mpt 4763 and
df-mpt2 6695). Contrast this predicate with the
predicates to determine
if some class is a function with a given domain (df-fn 5929), a function
with a given domain and codomain (df-f 5930), a one-to-one function
(df-f1 5931), an onto function (df-fo 5932), or a one-to-one onto function
(df-f1o 5933). For alternate definitions, see dffun2 5936, dffun3 5937,
dffun4 5938, dffun5 5939, dffun6 5941, dffun7 5953, dffun8 5954, and dffun9 5955.
(Contributed by NM, 1-Aug-1994.) |
