The semirings tag has no wiki summary.

**22**

votes

**0**answers

946 views

### Mikhalkin's tropical schemes versus Durov's tropical schemes

In Mikhalkin's unfinished draft book on tropical geometry, (available here) (page 26) he defines a notion of tropical schemes. It seems to me that this definition is not just a wholesale adaptation of ...

**12**

votes

**0**answers

405 views

### Categorification of the integers

I would like to know a natural categorification of the rig of integers $\mathbb{Z}$. This should be a $2$-rig. Among the various notions of 2-rigs, we obviously have to exclude those where $+$ is a ...

**7**

votes

**1**answer

190 views

### Semiring of vector bundles on $\mathbb{C}\mathbb{P}^1$

Consider the semiring
$$\mathbb{N}[H,H^{-1}]/(H^p+H^q = H^{p+q}+1)_{p,q \in \mathbb{Z}}.$$
Is it finitely presentable? Is there any simplification of the relations (except for $p \geq q \geq 0$)?
...

**7**

votes

**2**answers

336 views

### Integration on Compact Semirings

I want to know if integration of functions $f:X\rightarrow G$ where $G$ is a compact semiring has been defined and if it is possible to ensure that all continuous functions are integrable. This is ...

**4**

votes

**0**answers

94 views

### moduli in real/semi algebraic geometry

Is there a moduli space in semialgebraic geometry analogous to the Hilbert scheme in algebraic geometry?
The sort of thing I am imagining is an object in a category of semischemes:
Ordinary schemes ...

**3**

votes

**1**answer

184 views

### Looking for interesting, natural models of this algebraic theory in which $x^\dagger$ is not always the multiplicative inverse of $x$

It is easy to think up interesting, natural models of the algebraic theory presented as follows, such that in these models, $x^\dagger$ is always the multiplicative inverse of $x$.
Question. What ...

**3**

votes

**0**answers

124 views

### Semirings where solving linear systems is in P

Solving linear systems appears hard in semirings.
In $\mathbb{N}_0 (+,\times)$ it is NP-complete via reduction to 1-in-3 SAT.
In the min-plus semiring the complexity is $ NP \cap coNP$ according to ...

**2**

votes

**1**answer

135 views

### Terminology for the equation $a=a+b$ in commutative semigroups

Let $(S,+)$ be a commutative semigroup. For $a,b\in S$ consider the equation $a=a+b$. Does such a relation between the given $a$ and $b$ have a name? I am currently using such equations quite often ...

**2**

votes

**1**answer

272 views

### Semirings with subtractive primes

Let $S$ be a commutative semiring with identity such that each prime ideal of $S$ is subtractive. Does this imply all ideals of $S$ to be subtractive?
By a commutative semiring with identity I mean ...

**2**

votes

**1**answer

246 views

### Dual of idempotent semirings

By an idempotent semiring I mean a set equipped with a join-semilattice with bottom structure $(0,+)$ and a multiplicative monoid $(1,\cdot)$ such that the following equations hold:
$a \cdot (b + c) ...

**2**

votes

**0**answers

86 views

### Quotients of the initial semiring

The natural numbers are the initial commutative semiring. Thus, for any commutative semiring $R$, there is a unique semiring map $\mathbb{N}\to R$.
For which $R$ is this map an epimorphism?
Some ...

**1**

vote

**2**answers

384 views

### Semiring naturally associated to any monoid?

For any monoid $M$, we can naturally construct a semiring $S$ as follows:
Let the additive monoid of $S$ be the free commutative monoid on $M$
Let the multiplicative monoid of $S$ be $M$
Then, if ...

**1**

vote

**0**answers

80 views

### q-product semiring

q-product is defined as
$x \otimes _q y = (x^{1-q}+y^{1-q}-1)^{1/(1-q)}$
Observation:
$(+,\otimes_\infty)$ is min-plus tropical semiring on the segment $[0,1]$
$(+,\otimes_1)$ is R
...

**1**

vote

**0**answers

124 views

### Substitution semiring?

Let G be a [ CF ] grammar, and let elements of semiring be sets of rules.
Define multiplication as:
$$ x\otimes y = \{ t| \exists r \in x \exists s \in y (t=subst(r,s))\} $$
where $subst(r,s)$ ...

**0**

votes

**2**answers

290 views

### commutative rigs and the Grothendieck Group

If I start with a commutative rig, and apply the Grothendieck Group construction to it, twice, once to the additive structure and once to the multiplicative structure, is the result well-known? Does ...

**0**

votes

**0**answers

65 views

### What is a necessary and sufficient condition that the kernel of a semi-module homomorphism is a partitioning sub-semi-module?

I would like to identify a representation of the subcategory of a comma category of semi-rings, whose objects are abelian group objects.
When attempting to identify the representation, the following ...

**-1**

votes

**1**answer

172 views

### An extension of the real semiring with multiple degrees of infinity

Is it possible to define an extension of the probability semiring $(\mathbb{R}^+, +, \times, 0, 1)$ such that
Closure $a^* = 1 + a + a^2 + \ldots$ is defined for every element of the semiring, not ...