st: Question on data manipulation

["Andre pierre" <hcpats@hotmail.fr>]

Dear Stata users,

I have a question, for which the answer might be simple, but I did not find 
it yet.
I am working on a datset that contains information on innovating firms. My 
question might be more understandable with the following example:
Firm 1 has 3 innovations (A, B and C). A and B have one caracteristic in 
common (x); B and C have another caracteristic in common (g), while 
Innovation D does not have the same caracteristic as any of the other 
innovations.
I would like to create a dummy that takes the value one if an invention by a 
given firm has at least one caracteristic in common with one of the other 
innovations by the the same firm. My question is how can I get this dummy?

Firm; innovation; carateristic; dummy
1; A; x; 1
1; A; y; 1
1; A; z; 1
1; B; x; 1
1; B; g; 1
1; C; g; 1
1; D; f; 0

Thanks,
Andr�

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