BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Wijnand Steneker DTSTART:20260408T162000Z DTEND:20260408T180000Z DTSTAMP:20260423T005853Z UID:GDEq/155 DESCRIPTION:Title: O n globally invariant Euler-Lagrange equations for curves\nby Wijnand S teneker as part of Geometry of differential equations seminar\n\n\nAbstrac t\nInvariant Lagrangians yield invariant Euler-Lagrange equations and loca l methods for computing these are well-established\, starting with Anderso n and Griffiths. We focus on global algebraic invariants\, using an invar iant version of variational bicomplex or\, more generally\, C-spectral seq uence. One motivation is the question\, posed by Kogan and Olver\, whether invariant variational problems with only singular extremals can exist. We show that the example of conformal geodesics answers this question positi vely and motivates the need for global invariant methods. We then discuss how to compute invariant Euler-Lagrange equations using global invariants and how this can be applied in practice\, both as a supplementary tool for existing local methods\, as well as in a purely global setting. We demons trate these principles with some examples\, all for systems of ODEs (unpar ametrized curves). \n\nThis talk is based on joint work with Boris Krugli kov and Eivind Schneider (Tromsø).\n LOCATION:https://researchseminars.org/talk/GDEq/155/ END:VEVENT END:VCALENDAR