Extension card · Plithogenic
Plithogenic WPM
Plithogenic WPM is the form of WPM used when criterion assessments are given as a truth-indeterminacy-falsity triple and criteria carry a degree of contradiction relative to one another. Once adjusted by this contradiction degree, criteria are combined through a weighted geometric aggregation operator (PNWG-like) and reduced to a single score.
Base method
WPM →
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?
Three things change; the multiplicative logic does not.
Cells. In crisp WPM every cell is a single, strictly positive number. Here every cell is a truth (T), indeterminacy (I), falsity (F) triple. As on the plithogenic data-type card, one criterion is taken as dominant, with a contradiction degree of zero; how far each other criterion opposes the dominant one is given by a contradiction degree between 0 and 1. Criterion weights are a separate, externally supplied input, distinct from the contradiction degree.
Cost complementation and contradiction adjustment. Crisp WPM inverts a cost criterion in a single step: it divides the cell into the column's smallest value. Here, direction is handled the same way, at cell level and at an early step. The cost criterion's triple is first complemented to (F, I, T), and every cell is then adjusted by its own criterion's contradiction degree (truth grows towards the dominant criterion, while indeterminacy and falsity shrink by the same proportion). This order — complement first, then adjust for contradiction — is how DecisionMind carries crisp WPM's "ratio every cell directly" logic into the plithogenic family. The same family's WISP-based member (Plithogenic WISP), by contrast, never complements the cost criterion at all, because crisp WISP itself never inverts any column on its own.
Aggregation and defuzzification. The contradiction-adjusted triples are combined through a weighted geometric aggregation operator. Combined truth is computed multiplicatively, as Π T_j^{w_j}; combined indeterminacy and combined falsity are each computed in probabilistic-sum form, as 1 − Π(1−I_j)^{w_j} and 1 − Π(1−F_j)^{w_j}. Truth behaving multiplicatively while indeterminacy and falsity behave in a sum-like way means that WPM's unforgiving character towards a weak criterion is preserved in the truth component, while indeterminacy and falsity accumulate; this matches, term for term, the same aggregation rule used in the family's neutrosophic member (Neutrosophic WPM). The combined triple is reduced, in the final step, to a single number with the neutrosophic score function (s = (1 + T − 2I − F) / 2).
DecisionMind fixes the aggregation rule and the defuzzification score in this extension. Weights and contradiction degrees are taken from outside; the method itself generates neither weights nor contradiction degrees.
How to Read the Output
As in crisp WPM, the score is only a ranking; it holds within this alternative set and is neither a percentage nor a probability.
The difference lies here: beneath this score sit both the contradiction degree and a multiplicative truth aggregation. As shown on the Plithogenic CoCoSo card, in some DecisionMind engines the contradiction degree can end up having no effect at all on the result, because that engine's column-wise min-max scaling absorbs the linear transformation the contradiction produces. Plithogenic WPM has no such min-max scaling step; the contradiction adjustment feeds directly into the multiplicative aggregation. For this card, the kernel was tested directly in Python, and it was found that changing the contradiction degree genuinely changes the scores, and over certain ranges even reverses the ranking (see Case 1 and the verification notes).
Furthermore, because truth combines multiplicatively, a very low truth degree on a single criterion drags the combined truth down sharply, even if that criterion's weight is small. This shows that crisp WPM's unforgiving character towards a weak criterion holds here too.
Thus instead of writing:
"The contradiction degree has no effect on the result in Plithogenic WPM either, because this was proven for another member of the family"
the report should read:
"In this engine the contradiction degree genuinely changes the result, and under certain conditions can even reverse the ranking; which engine is sensitive to this parameter must be tested separately for every member of the family"
When to Prefer This over the Base Method
Consider this extension when your criterion scores are given as truth-indeterminacy-falsity triples and some criteria are a more independent, or more contradictory, source of information than others; the detail is covered on the Plithogenic data-type card. Crisp WPM's exit condition holds here too: criteria are expected to sit on a genuine ratio scale, and the matrix must be of a single type.
Mistakes Specific to This Extension
Complementing the cost criterion's triple but skipping the contradiction adjustment (or the reverse). The correct order is complementation first (F, I, T), then the contradiction adjustment; reversing this order, or skipping either step, produces a different result.
Assuming the contradiction degree is inert in this engine too. The inertness proven for Plithogenic CoCoSo is a property of that engine's min-max scaling. Plithogenic WPM has no such scaling step, and here the contradiction degree genuinely affects the result, enough in places to change the ranking.
Failing to notice that a single low truth degree can sharply pull down the combined score. The kernel has been tested directly in Python. In the illustrative example, when the indeterminacy degree is kept high on every criterion (around 0.90), the combined score can turn negative; this shows that crisp WPM's refusal to forgive a weak criterion holds in the plithogenic form too.
Choosing the dominant criterion arbitrarily. Because the contradiction degree has a real effect in this engine, the decision of which criterion counts as dominant (zero contradiction) matters here in particular and must be justified in the report.
The governing principle is this:
In Plithogenic WPM the cost criterion is complemented first, then adjusted by the contradiction degree; because the truth component combines multiplicatively, both the contradiction degree and a single weak criterion have a real, measurable effect on the result.
Cases
The first case is DecisionMind's validation example. Smarandache's founding 2018 source defines the plithogenic operations (including the contradiction adjustment) but contains no WPM decision-table example; DecisionMind has therefore built a small, hand-traceable table with the same formulas. This table is the shared 3×3 synthetic fixture also used by other members of the same family (Plithogenic CoCoSo, Plithogenic WISP). The second case is an illustrative construction.
1. Illustrative example (DecisionMind's validation example): Plithogenic evaluation of three suppliers
Three suppliers are evaluated on three criteria. The first two criteria are "more is better", the third is "less is better". The first criterion is taken as dominant, with a contradiction degree of zero; the second and third criteria's contradiction degrees relative to the first are 0.33 and 0.67 respectively.
| Supplier | Criterion 1 (more is better) | Criterion 2 (more is better) | Criterion 3 (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 |
| Weight | 0.40 | 0.35 | 0.25 |
The method complements the cost criterion, adjusts every cell by its own criterion's contradiction degree, combines them through the weighted geometric aggregation operator, and reduces the result to a score.
| Supplier | Score | Rank |
|---|---|---|
| A2 | 0.7201 | 1 |
| A3 | 0.6227 | 2 |
| A1 | 0.6032 | 3 |
The result reads as follows. A2 has the highest truth degree (0.80) on the first criterion; because truth combines multiplicatively, this advantage carries through across all criteria and puts A2 clearly ahead.
The supplier's hesitation is whether the contradiction degree has a real effect at all. On the family's Plithogenic CoCoSo card, the contradiction degree was proven to have no effect on the result whatsoever. Here the situation is different: if the second criterion's contradiction degree is raised from 0.33 to 0.60 (holding the first and third criteria fixed), A1 and A3 swap places, with A1 moving from third to second (score_A1≈0.663, score_A3≈0.657); A2 keeps first place under every setting. This sensitivity was computed independently in Python.
In the report: "With the contradiction degrees given, A2 takes the highest score (0.7201), and this first place is robust. The second and third places (A3, A1), however, are sensitive to the contradiction-degree estimate; raising the second criterion's contradiction degree can swap these two suppliers."
Source: DecisionMind's Plithogenic WPM validation example. The plithogenic operations (contradiction adjustment, aggregation, score function) rest on the formulas defined by Smarandache (2018); since the founding source gives no WPM decision-table example, the table was constructed by DecisionMind faithfully to the formulas and is shared with the other members of the family. The scores and the contradiction-degree sensitivity test were verified by this card's author by independently recomputing the kernel logic in Python.
2. Textiles: A garment manufacturer's choice of fabric supplier
A garment manufacturer will choose one of three fabric-supplier quotations (K1, K2, K3) for a new collection. Two criteria are "more is better": fabric quality and colour consistency; the third criterion is unit cost ("less is better"). Because it knows fabric quality largely from laboratory test reports, the manufacturer has taken it as the dominant criterion, and has set the contradiction degrees on the view that colour consistency carries information partly linked to quality, while cost carries more independent information.
The method complements the three quotations, adjusts them by the contradiction degrees, combines them multiplicatively, and reduces the result to a score. Suppose the quotation with the highest fabric quality comes out ahead, since its cost is also low; the quotation with the highest colour consistency comes second.
The manufacturer's hesitation: on the colour-consistency criterion, one quotation has been entered with a low truth degree and a high indeterminacy, because only a single sample batch has so far been seen from this supplier. Because truth combines multiplicatively, this single low value may be pulling that quotation's overall score down sharply, regardless of its weight. The manufacturer should not consider eliminating this quotation before seeing a second sample batch.
In the report: "Weighted by fabric quality and cost, K1 is ahead. K3's low standing owes much to the low truth degree entered for colour consistency, based on a single sample; updating this degree after a second sample batch is recommended."
3. What Not to Do
The first error is feeding the illustrative example's cost criterion (Criterion 3) straight into the contradiction adjustment without complementing it first; this carries over a step that belongs to another member of the family (Plithogenic WISP) and unfairly rewards the highest-cost supplier. The second error is entering the contradiction degree in this engine, too, with an arbitrary, unjustified value, on the grounds that "Plithogenic CoCoSo showed the contradiction degree had no effect"; this family requires engine-by-engine verification. The third error is reading a low-scoring alternative as "weak on every criterion" without ever testing how much a low truth degree on a single criterion can pull the combined score down.
Sources
For the formulas behind each step, the intermediate tables and citation formats, see the DecisionMind method page: decisionmind.app/library/p-wpm
Miller, D. W., & Starr, M. K. (1969). Executive Decisions and Operations Research. Prentice-Hall. (no DOI; the founding source of crisp WPM.)
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)
Ye, J. (2014). A multicriteria decision-making method using aggregation operators for simplified neutrosophic sets. Journal of Intelligent & Fuzzy Systems, 26(5), 2459–2466. DOI: 10.3233/IFS-130916