{"title":"On the microlocal regularity of the Gevrey vectors for second order partial differential operators with non negative characteristic form of first kind","authors":"Gregorio Chinni, Makhlouf Derridj","doi":"10.1007/s10231-026-01698-w","DOIUrl":"10.1007/s10231-026-01698-w","url":null,"abstract":"<div><p>We study the microlocal regularity of the analytic/Gevrey vectors for the following class of second order partial differential equations </p><div><div><span>$$begin{aligned} P(x,D) = sum _{ell ,j=1}^{n} a_{ell ,j}(x) D_{ell } D_{j} + sum _{ell =1}^{n} i b_{ell }(x) D_{ell } +c(x), end{aligned}$$</span></div></div><p>where <span>(a_{ell ,j}(x) = a_{j,ell }(x))</span>, <span>(b_{ell }(x))</span>, <span>(ell ,j in lbrace 1,dots ,, nrbrace )</span>, are real valued real Gevrey functions of order <i>s</i> and <i>c</i>(<i>x</i>) is a Gevrey function of order <i>s</i>, <span>(s ge 1)</span>, on <span>(Omega )</span> open neighborhood of the origin in <span>({mathbb {R}}^{n})</span>. Thus providing a microlocal version of a result due to Derridj in (Complex Anal. Synerg. 6:10, 2020). The class of operators considered in this work generalizes the classes studied by Braun Rodrigues-Chinni-Cordaro-Jahnke (Proc. Am. Math. Soc. 144:5159–5170, 2016) and Chinni-Derridj (Math. Z. 302:1983–2003, 2022).</p></div>","PeriodicalId":8265,"journal":{"name":"Annali di Matematica Pura ed Applicata","volume":"205 6","pages":"3053 - 3110"},"PeriodicalIF":0.9,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10231-026-01698-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149309802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Reflections and Drinfeld twists for set-theoretic Yang–Baxter maps","authors":"Davide Ferri","doi":"10.1007/s10231-026-01703-2","DOIUrl":"10.1007/s10231-026-01703-2","url":null,"abstract":"<div><p>The Yang–Baxter equation (<span>ybe</span>) and the reflection equation (<span>re</span>) both come from mathematical physics, and they can be defined in any monoidal category. For cartesian monoidal categories, we prove that every solution to the <span>re</span> provides a Drinfeld twist for a solution of the <span>ybe</span>. As we observe, Drinfeld twists of solutions are relevant for the following reason: two solutions to the <span>ybe</span> (in any strict monoidal category) are related by a Drinfeld twist, if and only if they induce equivalent representations of the braid group. In the category of sets, it is known that every solution is associated with a structure group, which is a braided group in the sense of Lu et al. (Duke Math J 104(1):1–18, 2000). Using De Commer’s notion of a braided action, we then define group reflections for a braided group. We prove that group reflections provide group Drinfeld twists in the sense of Ghobadi. Finally, we characterise when a reflection on a solution (<i>X</i>, <i>r</i>) can be extended to a group reflection on its structure group <i>G</i>(<i>X</i>, <i>r</i>).</p></div>","PeriodicalId":8265,"journal":{"name":"Annali di Matematica Pura ed Applicata","volume":"205 6","pages":"3213 - 3243"},"PeriodicalIF":0.9,"publicationDate":"2026-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10231-026-01703-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149309593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Boundary regularity for parabolic systems with nonstandard (p,q)-growth conditions in smooth convex domains","authors":"Michael Strunk","doi":"10.1007/s10231-026-01708-x","DOIUrl":"10.1007/s10231-026-01708-x","url":null,"abstract":"<div><p>We study the boundary regularity of local weak solutions to nonlinear parabolic systems of the form </p><div><div><span>$$begin{aligned} partial _t u^i - textrm{div} big ( a(|Du|) Du^i big )= f^i, qquad i=1,dots ,N, end{aligned}$$</span></div></div><p>in a space-time cylinder <span>(Omega _T = Omega times (0,T))</span>, where <span>(Omega subset mathbb {R}^n)</span> (<span>(n ge 2)</span>) is a bounded, convex <span>(C^2)</span>-domain and <span>(T>0)</span>. The inhomogeneity <span>(f=(f^1,dots ,f^N))</span> belongs to <span>(L^{n+2+sigma }(Omega _T,mathbb {R}^N))</span> for some <span>(sigma >0)</span>. The coefficients <span>(a:mathbb {R}_{>0} rightarrow mathbb {R}_{>0})</span> are of Uhlenbeck-type and satisfy a nonstandard (<i>p</i>, <i>q</i>)-growth condition with </p><div><div><span>$$ 2 le p le q < p + frac{4}{n+2}. $$</span></div></div><p>Our main result establishes a local Lipschitz estimate up to the lateral boundary for any local weak solution that vanishes on the lateral boundary of the cylinder.</p></div>","PeriodicalId":8265,"journal":{"name":"Annali di Matematica Pura ed Applicata","volume":"205 6","pages":"3313 - 3350"},"PeriodicalIF":0.9,"publicationDate":"2026-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10231-026-01708-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149310415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Robustness and dichotomy radii for discrete dynamics on the half-line","authors":"Davor Dragičević, Adina Luminiţa Sasu, Bogdan Sasu","doi":"10.1007/s10231-026-01710-3","DOIUrl":"10.1007/s10231-026-01710-3","url":null,"abstract":"<div><p>We present a complete study on the dichotomy roughness and dichotomy radii for nonautonomous discrete dynamics on the half-line, in infinite-dimensional spaces. Our approach is based on new characterizations of the uniform exponential dichotomy that extend the results in [72]. We prove novel criteria for the robustness of the uniform exponential dichotomy, providing general bounds for the perturbations that preserve it. We introduce for the first time the notions of <i>dichotomy radius</i> on the half-line and of <i>dichotomy radius relative to a subspace</i> and obtain lower bounds for both of these radii. Furthermore, we determine an interval in which the dichotomy radius relative to an unstable subspace varies, expressed in terms of input–output operators. Using explicit examples, we show that the bounds and the dichotomy radii can be calculated, and in certain cases these radii may coincide. All the results are obtained in the most general framework, without imposing any additional hypotheses on the coefficients of the original or perturbed systems or on their propagators.</p></div>","PeriodicalId":8265,"journal":{"name":"Annali di Matematica Pura ed Applicata","volume":"205 6","pages":"3365 - 3406"},"PeriodicalIF":0.9,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10231-026-01710-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149310320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Talenti comparison result for a weighted Poisson equation with Neumann boundary value","authors":"Yifei Dai, Xiaomei Sun, Anqiang Zhu","doi":"10.1007/s10231-026-01711-2","DOIUrl":"10.1007/s10231-026-01711-2","url":null,"abstract":"<div><p>In this paper, we establish a comparison theorem between positive solutions of the weighted Poisson equation with nonhomogeneous Neumann boundary conditions and suitable positive solutions of its Schwarz symmetrized problem satisfying appropriate matching boundary conditions. We also prove comparison results for the weighted Poisson equation with homogeneous Neumann boundary conditions. Our main tools include weighted isoperimetric inequalities and symmetrization techniques.</p></div>","PeriodicalId":8265,"journal":{"name":"Annali di Matematica Pura ed Applicata","volume":"205 6","pages":"3407 - 3427"},"PeriodicalIF":0.9,"publicationDate":"2026-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149309721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marcos M. Alexandrino, Leonardo F. Cavenaghi, Diego Corro, Marcelo K. Inagaki
{"title":"Singular Riemannian foliations, variational problems and principles of symmetric criticalities","authors":"Marcos M. Alexandrino, Leonardo F. Cavenaghi, Diego Corro, Marcelo K. Inagaki","doi":"10.1007/s10231-026-01679-z","DOIUrl":"10.1007/s10231-026-01679-z","url":null,"abstract":"<div><p>A singular foliation <span>(mathscr {F})</span> on a complete Riemannian manifold <i>M</i> is called a Singular Riemannian foliation (SRF for short) if its leaves are locally equidistant, e.g., the partition of <i>M</i> into the orbits of a Lie group action by isometries. In this paper, we investigate variational problems in compact Riemannian manifolds equipped with SRFs with special properties, which we name as AVP. Examples of such SRFs being considered include isoparametric foliations, SRFs on Euclidean fiber bundles, and the partition of <i>M</i> into the orbits of a Lie group acting by isometries. More precisely, we prove an analog to Palais’ Principle of Symmetric Criticality for <span>(mathscr {F})</span>-symmetric integral operators on the Banach spaces <span>(W^{1,p}(M).)</span> This result together with a version of the Rellich–Kondrachov–Hebey–Vaugon Embedding Theorem for <span>(mathscr {F})</span>-basic Sobolev functions allows us to circumvent difficulties with Sobolev’s critical exponents when considering applications of techniques from Calculus of Variations to find solutions to PDEs. To exemplify this, we prove the existence of countably infinite many weak solutions to a class of variational problems, which includes <i>p</i>-Kirchhoff problems for manifolds equipped with an AVP foliation.</p></div>","PeriodicalId":8265,"journal":{"name":"Annali di Matematica Pura ed Applicata","volume":"205 5","pages":"2507 - 2572"},"PeriodicalIF":0.9,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10231-026-01679-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Correction to: The rigidity of biconservative surfaces in Sol3","authors":"Dorel Fetcu","doi":"10.1007/s10231-026-01707-y","DOIUrl":"10.1007/s10231-026-01707-y","url":null,"abstract":"<div><p>We correct an error in a formula in [1] by adding a supplementary natural geometric hypotesis on the considered surfaces.</p></div>","PeriodicalId":8265,"journal":{"name":"Annali di Matematica Pura ed Applicata","volume":"205 6","pages":"3311 - 3312"},"PeriodicalIF":0.9,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149310472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A family of stochastic pre-orders based on the usual stochastic order","authors":"Francesco Buono, Maria Longobardi","doi":"10.1007/s10231-026-01706-z","DOIUrl":"10.1007/s10231-026-01706-z","url":null,"abstract":"<div><p>A new family of stochastic pre-orders is introduced. We focus on the cases in which two variables are not comparable in the usual stochastic order and study how close they are to be comparable in such order. In particular, we require that the difference between the cumulative distribution functions of the random variables does not change sign up to a certain quantile. Then, the higher the order of the quantile, the closer is the relation to the standard usual stochastic order. An analogous definition can be given in terms of upper quantiles as well, and the one associated to the quantile of higher order has to be preferred. We study some properties of the proposed pre-orders and some connections with other stochastic orders. Then, these relations are applied in the context of reliability theory based on residual and past lifetimes. Finally, they are employed in the study of lifetimes of coherent systems under different assumptions on the components’ lifetimes.</p></div>","PeriodicalId":8265,"journal":{"name":"Annali di Matematica Pura ed Applicata","volume":"205 6","pages":"3293 - 3309"},"PeriodicalIF":0.9,"publicationDate":"2026-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10231-026-01706-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149310134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alessandro Fonda, Maurizio Garrione, Andrea Sfecci
{"title":"On the period map of planar Hamiltonian systems with separated variables","authors":"Alessandro Fonda, Maurizio Garrione, Andrea Sfecci","doi":"10.1007/s10231-026-01709-w","DOIUrl":"10.1007/s10231-026-01709-w","url":null,"abstract":"<div><p>We consider planar Hamiltonian systems with Hamiltonian function of the type <span>(H(x,y)=F(y)+G(x))</span> having the origin as a global center, and generalize to this setting some known results on the period map. We are thus led to a characterization of isochronism for scalar second order equations involving the <i>p</i>-Laplacian operator.</p></div>","PeriodicalId":8265,"journal":{"name":"Annali di Matematica Pura ed Applicata","volume":"205 6","pages":"3351 - 3363"},"PeriodicalIF":0.9,"publicationDate":"2026-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10231-026-01709-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149310275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Symmetry breaking in biharmonic equations with weighted exponential nonlinearities","authors":"Marta Calanchi, Cristina Tarsi","doi":"10.1007/s10231-026-01700-5","DOIUrl":"10.1007/s10231-026-01700-5","url":null,"abstract":"<div><p>We investigate a class of fourth-order elliptic problems involving exponential-type nonlinearities and spatial weights of Hénon type. Motivated by the symmetry-breaking phenomena observed in semilinear second-order problems—such as those governed by the Hénon equation—we consider weighted functionals of the form </p><div><div><span>$$begin{aligned} F_m(u) = int _B |x|^alpha left( e^{sigma |u|^2} - sum _{k=0}^m frac{sigma ^k}{k!} |u|^{2k} right) dx, end{aligned}$$</span></div></div><p>defined on the unit ball <span>( B subset mathbb {R}^4 )</span>, where <span>(min mathbb N_0)</span> <span>( alpha > 0 )</span>, <span>( sigma >0)</span> are suitable parameters. We first establish an Adams-type inequality with weight, characterizing the sharp threshold for the boundedness of <span>( F )</span> on the unit sphere of the biharmonic Sobolev space. Then, we prove that for large values of the weight exponent <span>( alpha )</span>, radial symmetry of maximizers is broken. These results extend classical findings in the second-order setting (e.g., Trudinger–Moser-type functionals and the weighted Hénon equation) to the biharmonic context and offer new insights into the interplay between weights, nonlinearity, and symmetry in higher-order PDEs.</p></div>","PeriodicalId":8265,"journal":{"name":"Annali di Matematica Pura ed Applicata","volume":"205 6","pages":"3155 - 3178"},"PeriodicalIF":0.9,"publicationDate":"2026-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10231-026-01700-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149310068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}