{"title":"Extrapolation to mixed Herz spaces and its applications","authors":"Mingquan Wei","doi":"10.1002/mana.202100134","DOIUrl":"10.1002/mana.202100134","url":null,"abstract":"<p>In this paper, we extend the extrapolation theory to mixed Herz spaces <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msubsup>\u0000 <mover>\u0000 <mi>K</mi>\u0000 <mo>̇</mo>\u0000 </mover>\u0000 <mover>\u0000 <mi>q</mi>\u0000 <mo>⃗</mo>\u0000 </mover>\u0000 <mrow>\u0000 <mi>α</mi>\u0000 <mo>,</mo>\u0000 <mi>p</mi>\u0000 </mrow>\u0000 </msubsup>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <msup>\u0000 <mi>R</mi>\u0000 <mi>n</mi>\u0000 </msup>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$dot{K}^{alpha,p}_{vec{q}}(mathbb {R}^n)$</annotation>\u0000 </semantics></math> and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msubsup>\u0000 <mi>K</mi>\u0000 <mover>\u0000 <mi>q</mi>\u0000 <mo>⃗</mo>\u0000 </mover>\u0000 <mrow>\u0000 <mi>α</mi>\u0000 <mo>,</mo>\u0000 <mi>p</mi>\u0000 </mrow>\u0000 </msubsup>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <msup>\u0000 <mi>R</mi>\u0000 <mi>n</mi>\u0000 </msup>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$K^{alpha,p}_{vec{q}}(mathbb {R}^n)$</annotation>\u0000 </semantics></math>. To prove the main result, we first study the dual spaces of mixed Herz spaces, and then give the boundedness of the Hardy–Littlewood maximal operator on mixed Herz spaces. By using the extrapolation theorems, we obtain the boundedness of many integral operators on mixed Herz spaces. We also give a new characterization of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <mi>bounded</mi>\u0000 <mspace></mspace>\u0000 <mi>mean</mi>\u0000 <mspace></mspace>\u0000 <mi>oscillation</mi>\u0000 <mspace></mspace>\u0000 <mi>space</mi>\u0000 </mrow>\u0000 <mspace></mspace>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>BMO</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <msup>\u0000 <mi>R</mi>\u0000 <mi>n</mi>\u0000 </msup>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annot","PeriodicalId":49853,"journal":{"name":"Mathematische Nachrichten","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140034771","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":"Totally geodesic Lagrangian submanifolds of the pseudo-nearly Kähler \u0000 \u0000 \u0000 SL\u0000 (\u0000 2\u0000 ,\u0000 R\u0000 )\u0000 ×\u0000 SL\u0000 (\u0000 2\u0000 ,\u0000 R\u0000 )\u0000 \u0000 $mathrm{SL}(2,mathbb {R})times mathrm{SL}(2,mathbb {R})$","authors":"Mateo Anarella, J. Van der Veken","doi":"10.1002/mana.202300351","DOIUrl":"10.1002/mana.202300351","url":null,"abstract":"<p>In this paper, we study Lagrangian submanifolds of the pseudo-nearly Kähler <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>SL</mi>\u0000 <mo>(</mo>\u0000 <mn>2</mn>\u0000 <mo>,</mo>\u0000 <mi>R</mi>\u0000 <mo>)</mo>\u0000 <mo>×</mo>\u0000 <mi>SL</mi>\u0000 <mo>(</mo>\u0000 <mn>2</mn>\u0000 <mo>,</mo>\u0000 <mi>R</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation>$mathrm{SL}(2,mathbb {R})times mathrm{SL}(2,mathbb {R})$</annotation>\u0000 </semantics></math>. First, we show that they split into four different classes depending on their behavior with respect to a certain almost product structure on the ambient space. Then, we give a complete classification of totally geodesic Lagrangian submanifolds of this space.</p>","PeriodicalId":49853,"journal":{"name":"Mathematische Nachrichten","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140034744","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}