Suppose I have a square logical matrix M which I'm thinking of as a
relation between the row/column numbers.
I can make it into a symmetric relation (i.e. M[i,j] being TRUE implies
M[j,i] is TRUE) by the calculation
M <- M | t(M)
Is there a simple way to ensure transitivity, i.e. M[i,j] & M[j,k] both
being TRUE implies M[i,k] is TRUE?
The operation should only change FALSE or NA values to TRUE values; TRUE
values should never be changed.
Duncan Murdoch