Minor improvements of algorithm to solve under-defined systems of multivariate quadratic equations

There have been several works on solving an under-defined system of multivariate quadratic equations over a finite field, e.g. Kipnis et al. (Eurocrypt’98), Courtois et al. (PKC’02), Tomae-Wolf (PKC’12), Miura et al. (PQC’13), Cheng et al. (PQC’14) and Furue et al. (PQC’21). This paper presents two minor improvements of Furue’s aproach.