  We propose and study a variant of pliable index coding (PICOD) where
receivers have preferences for their unknown messages and give each unknown
message a preference ranking. We call this the preferential pliable
index-coding (PPICOD) problem and study the Pareto trade-off between the code
length and overall satisfaction metric among all receivers. We derive
theoretical characteristics of the PPICOD problem in terms of interactions
between achievable code length and satisfaction metric. We also conceptually
characterise two methods for computation of the Pareto boundary of the set of
all achievable code length-satisfaction pairs. As for a coding scheme, we
extend the Greedy Cover Algorithm for PICOD by Brahma and Fragouli, 2015, to
balance the number of satisfied receivers and average satisfaction metric in
each iteration. We present numerical results which show the efficacy of our
proposed algorithm in approaching the Pareto boundary, found via brute-force
computation.
