Adding definitions to a function

Questions
1

Hi,
Suppose I start with a simple function : F[x_]:=1;
I need to set F[k] equal to 0 for some k values.
For a single value, the following instructions do the job (Version 8.0) :

Clear[F]; F[x_] := 1; F[1] := 0;
Table[F[k], {k, 10}]
{0, 1, 1, 1, 1, 1, 1, 1, 1, 1}

However for a lot of values (say belonging to a lengthy list) the following doesn’t work :

Clear[F]; list = {1, 2, 3}; F /@ list := 0;
SetDelayed::write: Tag Map in F/@{1,2,3} is Protected. >>

Any idea about by what to write in place of F /@ list := 0; ?
Thanks in advance
Andre

2

One way:

Clear[f];
Map[(f[#] = 0) &, {1, 2, 3}]

Another way:

Clear[f];
list = {1, 2, 3};
Do[f[i] = 0, {i, list}]
3

The first solution is perfect, thanks a lot !