We consider the incompressible Euler equations on
class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0294144915000669&_mathId=si1.gif&_user=111111111&_pii=S0294144915000669&_rdoc=1&_issn=02941449&md5=726a2f7dbafbec3703a484c8652e27ce" title="Click to view the MathML source">Rdclass="mathContainer hidden">class="mathCode"> or
class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0294144915000669&_mathId=si2.gif&_user=111111111&_pii=S0294144915000669&_rdoc=1&_issn=02941449&md5=492be71637de168cb8088aac4c0ed05d" title="Click to view the MathML source">Tdclass="mathContainer hidden">class="mathCode">, where
class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0294144915000669&_mathId=si12.gif&_user=111111111&_pii=S0294144915000669&_rdoc=1&_issn=02941449&md5=a84fd0d53055809c867a2910d7ba330e" title="Click to view the MathML source">d∈{2,3}class="mathContainer hidden">class="mathCode">. We prove that:
(a) In Lagrangian coordinates the equations are locally well-posed in spaces with fixed real-analyticity radius (more generally, a fixed Gevrey-class radius).
(b) In Lagrangian coordinates the equations are locally well-posed in highly anisotropic spaces , e.g. Gevrey-class regularity in the label class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0294144915000669&_mathId=si4.gif&_user=111111111&_pii=S0294144915000669&_rdoc=1&_issn=02941449&md5=cc3b75844c59f3c500946e105b02a79f" title="Click to view the MathML source">a1class="mathContainer hidden">class="mathCode"> and Sobolev regularity in the labels class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0294144915000669&_mathId=si5.gif&_user=111111111&_pii=S0294144915000669&_rdoc=1&_issn=02941449&md5=393ac1da023f05c84ad1512f0d60d231" title="Click to view the MathML source">a2,…,adclass="mathContainer hidden">class="mathCode">.
(c) In Eulerian coordinates both results (a) and (b) above are false.