:: deftheorem defines flat PREFER_1:def 12 :
for P being PreferenceStr holds
( P is flat iff ( the ToleranceRel of P = id the carrier of P & ex a being Element of P st
( the PrefRel of P = [:{a},( the carrier of P \ {a}):] & the InternalRel of P = [:( the carrier of P \ {a}),( the carrier of P \ {a}):] ) ) );