[R] intersection of two matrices(updated)

[T Joshi]

Hi,

I have two matrices as follow:
matrix A =

a=matrix(c(c("abc","abc","bcd","bcd","bce","bce"),c("a1","d2","d1","d2","a1","a2")),6,2)

and matrix B which contains pair of values :
 b=matrix(c(c("a1","a1"),c("a2","d2")),2,2)


 In short, I wish to find out pairs of values in matrix a[,2] having
same value in a[,1], which occur as a row in matrix b, so that the
output becomes :
abc
bce, or

even better
abc a1 d2
bce a1 a2

 How can I do that?
cheers,
Joshi