
In the paper under review, the authors introduce the notion of residual normal crossing at a closed point of a variety \(X\) and observe that the \((p-1)\)-th power of a section \(s\) of \(K_X^{-1}\) (for a smooth variety \(X\) with the canonical bundle \(K_X)\) with a residual normal crossing at a closed point Frobenius splits the variety \(X\). This generalizes an earlier result due to Mehta and Ramanathan asserting that the \((p-1)\)-th power of a section \(s\) of \(K_X^{-1}\) with normal crossing divisor at some closed point Frobenius splits \(X\). In the present paper, it is further shown that for any parabolic subgroup \(Q\) of a simple group \(G\) of classical type or of type \(G_2\), \(K^{-1}_X\) (where \(X=G/Q)\) admits a section with residual normal crossing at the base point. This provides another proof of the Frobenius splitting of such an \(X\). Further the authors conjecture that for any homogeneous space \(X\) in characteristic \(p>0\), \(E\) is compatibly split in the blow-up \(B(X\times X)\) of \(X\times X\) along the diagonal \(\Delta\) with exceptional divisor \(E\). This is equivalent to showing that there exists a splitting of \(X\times X\) which vanishes to order \((\dim X)(p-1)\) generically along \(\Delta\). It is shown that this conjecture implies the Wahl conjecture on the surjectivity of the Gaussian map in characteristic \(p\). Recall that this was proved by the reviewer in characteristic 0 earlier [\textit{S. Kumar}, Am. J. Math. 114, No. 6, 1201-1220 (1992; Zbl 0790.14015)].
residual normal crossing, surjectivity of the Gaussian map, Frobenius splittings, Algebra and Number Theory, characteristic \(p\), Grassmannians, Schubert varieties, flag manifolds, Finite ground fields in algebraic geometry, Formal methods and deformations in algebraic geometry, homogeneous space, Divisors, linear systems, invertible sheaves, Wahl conjecture, Wahl's conjecture
residual normal crossing, surjectivity of the Gaussian map, Frobenius splittings, Algebra and Number Theory, characteristic \(p\), Grassmannians, Schubert varieties, flag manifolds, Finite ground fields in algebraic geometry, Formal methods and deformations in algebraic geometry, homogeneous space, Divisors, linear systems, invertible sheaves, Wahl conjecture, Wahl's conjecture
| citations This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 12 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Top 10% | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
