Graded identities for algebras with elementary gradings over an infinite field

Let $F$ be an infinite field of positive characteristic $p > 2$ and let $G$ be a group. In this paper, we study the graded identities satisfied by an associative algebra equipped with an elementary $G$ -grading. Let $E$ be the infinite-dimensional Grassmann algebra. For every $a$ , $b\in \mathbb {N}$ , we provide a basis for the graded polynomial identities, up to graded monomial identities, for the verbally prime algebras $M_{a,b}(E)$ , as well as their tensor products, with their elementary gradings. Moreover, we give an alternative proof of the fact that the tensor product $M_{a,b}(E)\otimes M_{r,s}(E)$ and $M_{ar+bs,as+br}(E)$ are $F$ -algebras which are not PI equivalent. Actually, we prove that the $T_{G}$ -ideal of the former algebra is contained in the $T$ -ideal of the latter. Furthermore, the inclusion is proper. Recall that it is well known that these algebras satisfy the same multilinear identities and hence in characteristic 0 they are PI equivalent.

Unbounded negativity on rational surfaces in positive characteristic

We give explicit blowups of the projective plane in positive characteristic that contain smooth rational curves of arbitrarily negative self-intersection, showing that the Bounded Negativity Conjecture fails even for rational surfaces in positive characteristic. As a consequence, we show that any surface in positive characteristic admits a birational model failing the Bounded Negativity Conjecture.

The Benefit of Autonomy and Control: A Positive Characteristic of the Home Health Aide Position

Home Health Aides’ (HHAs) are one of the fastest growing workforces in the country, yet the industry struggles to recruit new aides into the field and retain current workers. This study explored HHAs’ experiences with the level of autonomy and control granted to them within their day-to-day work. Findings from six focus groups with 37 HHAs showed that many aides select home care because of the control and independence the positions offer. Interacting one-on-one with clients and being able to self-structure their daily tasks were major benefits that drew HHAs to the field. Additionally, the HHAs highlighted the control they have over their schedule and the flexibility the position offers to enable them to accommodate other responsibilities, like childcare or other jobs. Being able to decline a client because of travel distance, the hours required, or not feeling that it is a “good fit” was also a welcomed aspect of the position. Despite complaints about the job, such as low pay, lack of benefits, and limited support, many of the HHAs admitted staying on in their positions because of the flexibility, autonomy, and control provided. Findings highlight the value that HHAs place on autonomy and control and the potential benefit that these job qualities have for promoting greater recruitment and retention of the home care workforce. Amplifying opportunities for these aspects of the job may thus entice new individuals to pursue a career as an HHA, as well as help to maintain those individuals currently in the position.

Which rational double points occur on del Pezzo surfaces?

We determine all configurations of rational double points that occur on RDP del Pezzo surfaces of arbitrary degree and Picard rank over an algebraically closed field $k$ of arbitrary characteristic ${\rm char}(k)=p \geq 0$, generalizing classical work of Du Val to positive characteristic. Moreover, we give simplified equations for all RDP del Pezzo surfaces of degree $1$ containing non-taut rational double points.

Rank varieties and 𝜋-points for elementary supergroup schemes

We develop a support theory for elementary supergroup schemes, over a field of positive characteristic p ⩾ 3 p\geqslant 3 , starting with a definition of a π \pi -point generalising cyclic shifted subgroups of Carlson for elementary abelian groups and π \pi -points of Friedlander and Pevtsova for finite group schemes. These are defined in terms of maps from the graded algebra k [ t , τ ] / ( t p − τ 2 ) k[t,\tau ]/(t^p-\tau ^2) , where t t has even degree and τ \tau has odd degree. The strength of the theory is demonstrated by classifying the parity change invariant localising subcategories of the stable module category of an elementary supergroup scheme.

Wall-crossings and a categorification of K-theory stable bases of the Springer resolution

We compare the $K$ -theory stable bases of the Springer resolution associated to different affine Weyl alcoves. We prove that (up to relabelling) the change of alcoves operators are given by the Demazure–Lusztig operators in the affine Hecke algebra. We then show that these bases are categorified by the Verma modules of the Lie algebra, under the localization of Lie algebras in positive characteristic of Bezrukavnikov, Mirković, and Rumynin. As an application, we prove that the wall-crossing matrices of the $K$ -theory stable bases coincide with the monodromy matrices of the quantum cohomology of the Springer resolution.