# This is the undirected graphical model from Whittaker (1990).
data(coronary)
ug = empty.graph(names(coronary))
arcs(ug, ignore.cycles = TRUE) = matrix(
c("Family", "M. Work", "M. Work", "Family",
"M. Work", "P. Work", "P. Work", "M. Work",
"M. Work", "Proteins", "Proteins", "M. Work",
"M. Work", "Smoking", "Smoking", "M. Work",
"P. Work", "Smoking", "Smoking", "P. Work",
"P. Work", "Proteins", "Proteins", "P. Work",
"Smoking", "Proteins", "Proteins", "Smoking",
"Smoking", "Pressure", "Pressure", "Smoking",
"Pressure", "Proteins", "Proteins", "Pressure"),
ncol = 2, byrow = TRUE,
dimnames = list(c(), c("from", "to")))
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