are reported also in Ref. [@zhou2014semimetallic]. It is worthwhile to mention that the predictive values of velocities $v_F^x, v_F^y$, were evaluated via the slope of the bands in the $k_x$ and $k_y$ directions, respectively by the formula $v_F=E(k)/\hbar k$.

In a comprehensive study, Feng *et al.*  [@Boro] based on tight-binding analysis revealed that the Fermi velocities in borophene are approximately $v_F^x=6.1$ eV and $v_F^y=7.0$ eV Å, which are close to the Fermi velocity of graphene ($v_F=6.6$ eV Å). These values also confirmed by angle-resolved photoemission spectroscopy and first-principles calculations [@Boro].

As previously mentioned, the first principle calculations show that the same pair of Dirac cones, is revealed for $\beta_{12}/Ag(111)$ [@Boro]. The calculated Fermi velocity for $\beta_{12}/Ag(111)$ is approximately $v_F=3.5$ eV Å, which is in the same order of magnitude as the experimental value. The difference between the theoretical and experimental values might originate from the many-body interactions [@Boro].

A cat’s-cradle-like topological semimetal phase which looks like multiple hourglasslike band structures staggered together, was discovered by Fan *et al.* [@X.Fan2018]. An original effective Hamiltonian based on $k.p$ approximation was extracted for monolayer borophene and borophane, the first material class to realize such a semimetal phase, including the SOC effects. In this 