Extension card · Plithogenic
Plithogenic ROV
This is the form of ROV for situations where criterion scores are given as a truth-indeterminacy-falsity triple and criteria carry a degree of contradiction relative to one another. It ranks alternatives by a weighted sum score placed on a fixed [0,1] scale.
Base method
ROV →
Philosophy, mechanics, strengths and weaknesses are on the base method card; this card describes only the difference.
Data type (family)
Plithogenic →
What this data type is, when to use it, how to write it in a cell: the family's full account is here.
What Changes from the Base Method?
Cells. In crisp ROV every cell is a single number. Here every cell is a truth (T), indeterminacy (I) and falsity (F) triple. One criterion is taken as dominant, with a contradiction degree of zero; the other criteria's opposition to the dominant one is given as a contradiction degree between 0 and 1. Criterion weights are supplied from outside as crisp numbers.
Contradiction adjustment, score and scale equalisation. For a cost criterion, the triple is complemented first. Each cell is then adjusted by its own criterion's contradiction degree and reduced to a single number with the neutrosophic score function ((1 + T − 2I − F)/2). Much as in crisp ROV's first step, this score is placed on a 0-to-1 scale between each criterion's own minimum and maximum; for a cost criterion this direction is reversed. Every column then reads in the "higher is better" direction.
An important structural difference: ROV's "two-state" split does not exist here. The defining feature of crisp ROV is that it splits the normalised criteria into TWO SEPARATE GROUPS: the weighted sum of the benefit criteria forms the best-case score, and the weighted sum of the (already direction-reversed) cost criteria forms the worst-case score; the final score is the AVERAGE of these two SEPARATE sums. The P-ROV kernel does not make this split. After direction-sensitive normalisation, ALL criteria, benefit and cost alike, are combined into a SINGLE weighted sum; this one sum is recorded as both the "best-case" and the "worst-case" value, and averaging the two returns the same number. In other words, reading the code shows that the worst-case variable is an EXACT COPY of the best-case variable; the "averaging" step here amounts to averaging a number with itself and changes nothing. The result is formally a single weighted sum; the two-state split that defines ROV has been lost. This is a finding verified by reading the code (see the verification notes); the card describes what the kernel actually produces, not what the manifest promises.
It can be shown that the contradiction degree never changes the result. The contradiction adjustment transforms every cell's score linearly, as s' = (1 − c)·s + c/2. Direction-sensitive normalisation is a pure min–max DIFFERENCE ratio, (s − smin)/(smax − smin); this ratio is UNCHANGED when every value in the column undergoes the same linear transformation, because the same scale and shift affect numerator and denominator alike and cancel out. An independent Python test showed that, across a wide range of contradiction degrees (from 0 to 0.95, in various combinations), the scores remained IDENTICAL to the decimal place (see the verification notes). This belongs to the same family as the ineffectiveness seen in P-CoCoSo and P-RAFSI.
DecisionMind fixes this score function and the min–max scale equalisation.
How to Read the Output
The score is a weighted sum on the [0,1] scale; a larger value is better. The principle from the crisp ROV card, that the score is meaningful only for this alternative set and these weights, applies here too.
The difference is here: in crisp ROV, an alternative's score is read as the average of its "optimistic" profile (the best case among the benefit criteria) and its "pessimistic" profile (the worst case among the cost criteria). This engine has no such split; the score is a single weighted sum of all criteria, equalised by direction. The sentence "the optimistic and pessimistic viewpoints were averaged" describes an operation that does not take place in this engine. The contradiction degree, for its part, has no measurable effect in this engine.
Thus instead of writing:
"The plithogenic ROV score, like crisp ROV, is the average of two separate optimistic and pessimistic views"
the report should read:
"In this engine, the P-ROV score is a SINGLE weighted sum of the direction-equalised criteria; the best-case/worst-case split that defines ROV is not computed here. The contradiction-degree parameter also has no measurable effect in this engine"
When to Prefer This over the Base Method
This extension can be considered when criterion evaluation rests on incomplete or contradictory information and a degree of contradiction between criteria is conceptually meaningful. But because of the finding above, in today's engine P-ROV does NOT provide the two-state split that defines ROV, and the contradiction degree contributes nothing to the result; this extension in practice operates as a direction-sensitive weighted sum, close to SAW. The detail is in the verification notes.
Turning a measured criterion into a T-I-F triple is not modelling uncertainty but producing it. If no compromise is acceptable on one criterion, the exit condition on the base ROV card applies unchanged.
Mistakes Specific to This Extension
Assuming P-ROV runs the same two-state split as crisp ROV. As proven above, this is wrong; the best-case and worst-case variables are copies of one another in the code.
Assuming the contradiction degree is effective, as in P-GRA. In P-ROV the contradiction degree does not change the result algebraically; assuming otherwise leads to a false sensitivity analysis.
Choosing the dominant criterion without justification. Even though the contradiction degree has no effect on the result, which criterion counts as dominant still matters for the consistency of data entry.
Skipping the cost complement. If (T, I, F) is not rewritten as (F, I, T), the highest-cost alternative appears to have been pulled towards the ideal.
The governing principle is this:
P-ROV takes its name from ROV but, in today's engine, does not run the best-case/worst-case split that defines ROV; the score is a single direction-sensitive weighted sum, and the contradiction degree does not algebraically affect this sum.
Cases
The first case is DecisionMind's validation example. This table is also a shared validation input used on other cards in the P-* family (Plithogenic CoCoSo, Plithogenic GRA, Plithogenic PSI, Plithogenic RAFSI, Plithogenic RAWEC). The second case is an illustrative construction.
1. Illustrative example (DecisionMind's validation example): Plithogenic evaluation of three alternatives on three criteria
Three alternatives are evaluated on three criteria. The first two criteria are "more is better", the third "less is better". C1 is taken as the dominant criterion, with a contradiction degree of zero; C2 and C3's contradiction degrees relative to C1 are 0.33 and 0.67 respectively. The weights are 0.40 for C1, 0.35 for C2 and 0.25 for C3.
| Alternative | C1 (more is better) | C2 (more is better) | C3 (less is better) |
|---|---|---|---|
| A1 | (0.70; 0.20; 0.10) | (0.50; 0.30; 0.20) | (0.60; 0.30; 0.20) |
| A2 | (0.80; 0.10; 0.10) | (0.60; 0.20; 0.20) | (0.40; 0.20; 0.30) |
| A3 | (0.60; 0.20; 0.20) | (0.70; 0.20; 0.10) | (0.50; 0.30; 0.20) |
| Contradiction degree | 0.00 | 0.33 | 0.67 |
The method complements C3, adjusts every cell by its own criterion's contradiction degree, reduces it to a score, places it on 0-to-1 by direction, and computes the weighted sum.
| Alternative | Score | Rank |
|---|---|---|
| A2 | 0.860 | 1 |
| A3 | 0.600 | 2 |
| A1 | 0.160 | 3 |
The result reads as follows. A2 sits at the best end of the column on both the dominant criterion, C1, and the cost criterion, C3 (once complemented); these two carry A2 clearly ahead. A1 has the weakest profile on all three criteria.
The board's hesitation lies in the contradiction degree. When the dominant criterion C1's contradiction degree is pulled from 0 to 0.95 and C2 and C3 are set to zero, independent recomputation shows the scores remain IDENTICAL to the decimal place (0.160 / 0.860 / 0.600). The same result is seen when C2 and C3 are both pulled to 0.95, and when every contradiction degree is set equal to 0.5. The board cannot use this parameter as a sensitivity test.
In the report: "With the weights given, A2 has the highest score (0.860); this ranking is robust to a weight swap. The contradiction-degree parameter has no measurable effect in this engine, and it has therefore not been presented in the report as an input that affects the result."
Source: DecisionMind's P-ROV validation example. The plithogenic operations (contradiction adjustment, score function) rest on the formulas defined by Smarandache (2018); since the founding source gives no ROV decision-table example, the table was constructed by DecisionMind faithfully to the formulas. The scores and the contradiction-degree sensitivity were independently computed by this card's author by running the kernel directly, and matched the manifest's recorded result exactly (A2 > A3 > A1, the same decimal values).
2. Care homes: A municipality's choice of care-home service provider
A municipality will choose one of three service-provider proposals for a new care home it is opening. Three criteria are used: quality of care staff, medical support capacity and monthly service fee (less is better). The municipality treats care-staff quality as the dominant criterion; it considers medical support capacity to be partly in contradiction with staff quality (a broader medical team generally requires a higher fee), and the fee to carry more independent information. Each proposal is scored on each criterion with a truth-indeterminacy-falsity triple.
The method adjusts the three proposals by their contradiction degrees, reduces them to scores, places them on 0-to-1 by direction, and computes the weighted sum. Suppose the proposal with the most qualified staff is also the most expensive, and still comes out first, because the weight on staff quality exceeds that on fee.
The municipality's hesitation is here: unlike crisp ROV, this score is not the "average of an optimistic and a pessimistic view"; staff quality and fee merge into the same single sum. If the municipality wants to see, separately, how far the staff-quality advantage offsets the fee disadvantage, that split is not offered by this engine; only the combined score can be reported.
In the report: "With the weight given to staff quality, the most qualified proposal ranks first; this score is a single weighted sum of the criteria and does not show the separate contribution of the optimistic and pessimistic views."
3. What Not to Do
The first error is presenting the P-ROV score, as in crisp ROV, as "the average of two separate measures"; no such split is computed in this engine. The second error is assuming the contradiction degrees behave as they do in P-GRA, treating them as "a sensitivity parameter that adjusts the result" and expecting a change in them to affect the outcome; in the illustrative example, even pulling the contradiction degrees to 0.95 leaves the scores identical to the decimal place. The third error is running C3 (less is better) without complementing it first; the most expensive alternative then appears to have been pulled towards the ideal.
Sources
For the formulas behind each step, the intermediate tables and citation formats, see the DecisionMind method page: decisionmind.app/library/p-rov
Yakowitz, D. S., Lane, L. J., & Szidarovszky, F. (1993). Multi-attribute decision making: Dominance with respect to an importance order of the attributes. Applied Mathematics and Computation, 54(2–3), 167–181. DOI: 10.1016/0096-3003(93)90057-l
Smarandache, F. (2018). Plithogenic Set, an Extension of Crisp, Fuzzy, Intuitionistic Fuzzy, and Neutrosophic Sets – Revisited. Neutrosophic Sets and Systems, 21, 153–166. DOI: 10.5281/zenodo.1408740
Smarandache, F. (2017). Plithogeny, Plithogenic Set, Logic, Probability, and Statistics. Pons Publishing House, Brussels. (no DOI)
Abdel-Basset, M., & Mohamed, R. (2020). A novel plithogenic TOPSIS-CRITIC model for sustainable supply chain risk management. Journal of Cleaner Production, 247, 119586. DOI: 10.1016/j.jclepro.2019.119586