:: deftheorem defines PI-preference-like PREFER_1:def 9 :
for P being PIStr holds
( P is PI-preference-like iff ( the PrefRel of P is asymmetric & the ToleranceRel of P is Tolerance of the carrier of P & the PrefRel of P /\ the ToleranceRel of P = {} & ( the PrefRel of P \/ ( the PrefRel of P ~)) \/ the ToleranceRel of P = nabla the carrier of P ) );