# unitree

• 2015, Fedor Pakovich, Alexander K. Zvonkin, “Minimum Degree of the Difference of Two Polynomials over ${\displaystyle \mathbb {Q} }$. Part II: Davenport-Zannier pairs”, in arXiv[1]:
When such a tree is uniquely determined by the set of black and white degrees of its vertices, it is called unitree, and the corresponding DZ-pair is defined over ${\displaystyle \mathbb {Q} }$.