https://revistas.uns.edu.ar/revuma <p>Revista de la Unión Matemática Argentina is an open access journal that publishes original research articles in all areas of pure and applied mathematics.</p> <p>&nbsp;</p> <p>We are currently using Open Journal Systems (OJS) to handle submissions. Please refer to <a title="Revista de la UMA" href="http://inmabb.criba.edu.ar/revuma/revuma.php" target="_self">our main website</a> for all other business with the journal.</p> Unión Matemática Argentina en-US Revista de la Unión Matemática Argentina 0041-6932 <p><span style="color: #111111; font-size: 11px; line-height: 15px;"><span style="color: #111111; font-size: 11px; line-height: 15px;">Authors who publish with this journal agree to the following terms:<br></span></span><br>Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a&nbsp;<a style="text-decoration: underline; color: #337755;" href="http://creativecommons.org/licenses/by/4.0/" target="_new">Creative Commons Attribution License</a>&nbsp;that allows others to share the work with an acknowledgment of the work's authorship and initial publication in this journal.&nbsp;<span style="font-weight: 400;">The Journal may retract the paper after publication if clear evidence is found that the findings are unreliable as a result of misconduct or honest error.</span></p> https://revistas.uns.edu.ar/revuma/article/view/3335 <p>In the present study, we investigate a new type of warped products on manifolds with indefinite metrics, namely, warped product lightlike submanifolds of indefinite Kaehler manifolds with a slant factor. First, we show that indefinite Kaehler manifolds do not admit any proper warped product semi-slant lightlike submanifolds of the type $N_{T}\times_{\lambda}N_{\theta}$, $N_{\theta}\times_{\lambda}N_{T}$, $N_{\perp}\times_{\lambda}N_{\theta}$ and $N_{\theta}\times_{\lambda}N_{\perp}$, where $N_{T}$ is a holomorphic submanifold, $N_{\perp}$ is a totally real submanifold and $N_{\theta}$ is a proper slant submanifold. Then, we study warped product semi-slant lightlike submanifolds of the type $B\times_{\lambda}N_{\theta}$, where $B = N_{T}\times N_{\perp}$, of an indefinite Kaehler manifold. Following this, we give one non-trivial example for this kind of warped products of indefinite Kaehler manifolds. Then, we establish a geometric estimate for the squared norm of the second fundamental form involving the Hessian of warping function $\lambda$ for this class of warped products. Finally, we present a sharp geometric inequality for the squared norm of second fundamental form of warped product semi-slant lightlike submanifolds of the type $B\times_{\lambda}N_{\theta}$.</p> Megha Pruthi Sangeet Kumar Copyright (c) 2024 Megha Pruthi, Sangeet Kumar http://creativecommons.org/licenses/by/4.0 2024-12-18 2024-12-18 68 1 1–21 1–21 10.33044/revuma.3335 https://revistas.uns.edu.ar/revuma/article/view/3622 <p>The copointed liftings of the Fomin–Kirillov algebra $\mathcal{FK}_3$ over the algebra of functions on the symmetric group $\mathbb{S}_3$ were classified by Andruskiewitsch and the author. We demonstrate here that those associated to a generic parameter are Morita equivalent to the regular blocks of well-known Hopf algebras: the Drinfeld doubles of the Taft algebras and the small quantum groups $u_{q}(\mathfrak{sl}_2)$. The indecomposable modules over these were classified independently by Chen, Chari–Premet and Suter. Consequently, we obtain the indocomposable modules over the generic liftings of $\mathcal{FK}_3$. We decompose the tensor products between them into the direct sum of indecomposable modules. We then deduce a presentation by generators and relations of the Green ring.</p> Cristian Vay Copyright (c) 2024 Cristian Vay http://creativecommons.org/licenses/by/4.0 2024-12-18 2024-12-18 68 1 23–48 23–48 10.33044/revuma.3622