3 papers
physics.gen-ph2026
Noether's theorem for the conditional principle of least action
S. L. Lyakhovich, S. B. Sayapin, I. A. Zubareva
We consider the problem of a conditional extremum of an action in a class of fields constrained by differential equations. For this setup, we propose an extension of Noether's firs…
math-ph2025
Gauge symmetry and partially Lagrangian systems
Simon Lyakhovich, Nikita Sinelnikov
We consider a classical field theory whose equations of motion follow from the least action principle, but the class of admissible trajectories is restricted by differential equati…
math-ph2025
Degree of freedom count in linear gauge invariant PDE systems
Simon Lyakhovich, Dmitri Piontkovski
We consider not necessarily Lagrangian partial linear differential equations (PDE) with constant coefficients. Einstein proposed a definition of the"strength" of such a field theor…