🚀 go-pugleaf

U = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }
A = { 1, 2, 3, 4, 5 }
B = { 4, 6, 7, 8, 9 }
C = { 0, 4, 7 }
D = { 1, 2, 3, 5 }
<1> How many functions satisfy D (= f( A, B, C ) ?
<2> Could somebody tell me where I can find questions similar to this one?
Thanks.

ps:
U                  universe
0                   null set
(=                 included in or equal to
(                   included in but not equal to
(-                  belong to
&                 intersection
|                    union
~                  complement

f( A, B, C )   set function, an expression of set operation that consist of
                     symbols 'A', 'B', 'C', '&', ' | ', '~' and parentheses.
                     all of expressions that are not consist of these
                     symbols are not set function.

                     example:
                      f( A, B, C ) = ~(A & ~B) | ~C
                      f( A, B, C ) = ~A & ~C
                      f( A, B, C ) = C
                     counterexample:
                      f( A, B, C ) = ~A & ~C | 0
                      f( A, B, C ) = U
                      f( A, B, C ) = A | D