# 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
• $(+,\otimes_{-\infty})$ is max-plus tropical semiring on $[0,\infty]$

Consider the following "generalized distributivity" law:

$x \otimes _q (y+z) = (x \otimes _p y)+(x \otimes _p z)$

I'm looking for closed form expression for $p$ in terms of $q$, or this is not feasible?

• The paper you link has a discussion of generalized distributivity in section 4.2, but it requires a modification of the addition operation. Apr 24 '16 at 12:06

It is very easy to see that this is not feasible. It suffices to try $q=0$, so we'd look for a function $f(\cdot,\cdot)$ such that $x+y+z-1=f(x,y)+f(x,z)$. As we can switch variables, this would yield $f\equiv const$, which is impossible.
• You can also set $z=y$ to find that $2f(x,y) = x + 2y - 1$, which is not symmetric in $x$ and $y$. Apr 24 '16 at 11:59