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some particular aspects concerning electre method applications

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1.The first original proposition (ELECTRE IV)<br />

In [4] the authors have proposed the next hierarchical relationship:<br />

If: c hg . ≥ c hg<br />

d gh ≤ d hg<br />

↔ A g is better than A h . ( A g P A h )<br />

where :<br />

c gh - the concordance indicator between the A g and A h alternatives;<br />

d gh - the discordance indicator between the A g and A h alternatives;<br />

This <strong>method</strong> has an inconvenience: even if both the alternatives (A g and A h ) have<br />

a major flaw, one of them will be accepted anyway, which is contrary to the principle of<br />

the original <strong>method</strong>, that doesn’t agree with accepting an alternative with a major flaw.<br />

Comparing our solution with the ELECTRE II <strong>method</strong> solution we can see that<br />

the hierarchical relationship we proposed:<br />

c gh ≥ c hg<br />

is identical with the ELECTRE II relationship:<br />

P + gh/ P - gh ≥ 1<br />

where:<br />

P + gh – is the amount of better criteria in favor of the A g alternative as comparing with the<br />

A h<br />

alternative.<br />

P - gh – is the amount of better criteria in favor of the A h alternative as comparing with the<br />

A g alternative.<br />

Our suggestion, which we can name the ELECTRE IV, is based on the following:<br />

the second relationship:<br />

d gh ≤ d hg<br />

can be completed by a third relationship, like d gh ≤ d, thus getting rid of the<br />

inconvenience; d is a discordance threshold, whose value is imposed by the decision<br />

maker (over 0,5 in our opinion).<br />

2. The second original proposition<br />

ELECTRE II <strong>method</strong> has proposed a concept of tough and mild hierarchy, which<br />

we can generalize, using the “hierarchical rank” – meaning the order in which we’ve<br />

done the hierarchy. How could we show this using a calculus?<br />

A suggestion might be the following: (ELECTRE V). In the hierarchical graph we<br />

can add an arrow every time the concordance or discordance threshold respectively<br />

changes. This may lead to the selection of the alternative for which we obtain a “better<br />

hierarchical difference” as comparing to the alternatives for which we get “mild<br />

hierarchical differences”.<br />

2

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