A nonfinitely based additively idempotent semiring of order four
Pith reviewed 2026-05-19 15:52 UTC · model grok-4.3
The pith
A 4-element additively idempotent semiring has no finite basis for its identities.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The authors prove a sufficient condition that forces an additively idempotent semiring to be nonfinitely based. They verify the condition on multiple examples, notably the semiring S_{(4,124)} of order four whose additive reduct has two minimal elements and two coatoms. It follows that these semirings have no finite basis for their identities.
What carries the argument
The sufficient condition for an additively idempotent semiring to be nonfinitely based, verified by checking structural features of its additive reduct.
If this is right
- The 4-element semiring S_{(4,124)} has no finite basis for its identities.
- Other additively idempotent semirings that meet the sufficient condition are likewise nonfinitely based.
- Nonfinite basis can occur among additively idempotent semirings of very small finite order.
Where Pith is reading between the lines
- The condition may help locate additional small nonfinitely based examples in this class of algebras.
- Analogous conditions could be sought for related structures such as semigroups or lattices.
- Classifying additively idempotent semirings by order according to whether they admit finite bases becomes a natural next question.
Load-bearing premise
The sufficient condition is valid and correctly holds for the 4-element semiring whose additive reduct has two minimal elements and two coatoms.
What would settle it
Deriving every identity of S_{(4,124)} from some finite list of identities would show that the semiring is in fact finitely based.
read the original abstract
We first establish a sufficient condition for an additively idempotent semiring to be nonfinitely based. As applications, we exhibit several examples of additively idempotent semirings satisfying this condition, including a $4$-element semiring $S_{(4,124)}$ whose additive reduct has two minimal elements and two coatoms. Consequently, these semirings have no finite basis for their identities.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper first establishes a sufficient condition for an additively idempotent semiring to be nonfinitely based. It then applies the condition to several examples, including the 4-element semiring S_{(4,124)} whose additive reduct has two minimal elements and two coatoms, and concludes that these semirings have no finite basis for their identities.
Significance. If the sufficient condition holds and is correctly verified on the given examples, the work supplies concrete small-order instances of nonfinitely based additively idempotent semirings. The explicit 4-element example is noteworthy for its minimality and may assist in mapping the boundary between finitely based and nonfinitely based varieties in this class of algebras.
minor comments (2)
- The abstract states that 'several examples' are exhibited but does not indicate their number or the orders involved beyond the 4-element case; a brief enumeration would improve clarity.
- Notation S_{(4,124)} is introduced without an immediate definition of the subscript; a short parenthetical explanation or forward reference to the construction in Section 3 would aid readability.
Simulated Author's Rebuttal
We thank the referee for the positive assessment of our manuscript, the recognition of the significance of the 4-element example, and the recommendation of minor revision. No specific major comments were provided in the report.
Circularity Check
No significant circularity; derivation is self-contained
full rationale
The paper first proves a general sufficient condition for an additively idempotent semiring to lack a finite equational basis, then verifies that the specific 4-element semiring S_{(4,124)} (whose additive reduct has two minimal elements and two coatoms) satisfies the hypotheses of that condition. This is a standard theorem-then-application structure with no reduction of the central claim to a fitted parameter, self-definition, or load-bearing self-citation. The verification for the small finite algebra is direct and independent of the result being proved.
Axiom & Free-Parameter Ledger
axioms (1)
- standard math Basic definitions and properties of semirings and idempotent addition
Reference graph
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