I'm currently studying the minimum weight $b$-matching problem. In the material I have for the problem, the author keeps mentioning integral vectors, but with no explanation to what it is.
An example is:
Given an undirected graph $G = (V,E)$, a cost $c_e$ for an edge $e \in E$ and $b_i \in \mathbb{Z}^{+}$ a parameter associated to the vertex $i \in V$.
The objective is to find a minimum weight integral vector $x \in \mathbb{Z}^{|E|}$, that minimises the total cost of the problem.
I can not find any mentioning of what an integral vector is?