Most complex decision problems involve conflicting multicriteria to be reco
nciled. It is not uncommon that the numerical values of alternatives of som
e criteria are subject to imprecision, uncertainty, and indetermination. Th
e concept of pseudo-criterion and its two thresholds allow them to be taken
into account. So far, outranking relation methods, which are called ELECTR
E I-IV and others, in which an outranking relation between alternatives is
constructed from pseudo-criteria have been developed. Among others, ELECTRE
III is the most familiar and has been widely used. The purpose of this pap
er is to propose a new procedure for treating the pseudo-criterion based on
the ternary AHP. This procedure differs from ELECTRE III and requires only
the incomplete information on the weights but not precise weights. Strict
preference, weak preference, and indifference relations associated with a p
seudo-criterion are formulated by a ternary comparison. In general, the pro
cedures for dealing with the pseudo-criterion necessarily involve a certain
amount of arbitrariness. Therefore, it is preferable to derive the ranking
s of alternatives from several procedures for the pseudo-criterion in order
to promote complementary viewpoints. Comparing our procedure with ELECTRE
III, the strengths and weaknesses of the proposed procedure are discussed.