Prove that the Lagrangian Density $\mathscr{L}$, which generates a given set of Euler-Lagrange equations, is not unique
29329
Does a four-divergence extra term in a Lagrangian density matter to the field equations?
116513
Distributional Laplacian of logarithm and the Dirac delta distribution
94058
Applying the Berry-Esseen theorem to non-identically distributed summands
109187
The differences between Lagrange and Leibniz's derivative notations
89089
Prove that there is a unique inner product on $V$
66919
When/why does the principle of least action plus boundary conditions not uniquely specify a path?
26658
A proof for $\nabla |u|^p = p\ \text{sgn}(u)|u|^{p-1}\nabla u$.
4421
Proof that total derivative is the only function that can be added to Lagrangian without changing the EOM
70606
Show that the LU decomposition of matrices of the form $\left[\begin{smallmatrix}0& x\\0 & y\end{smallmatrix}\right]$ is not unique
18125
Counterexamples to the converse to Lagrange's Theorem different from $A_{4}$.
150674
Uniqueness in existence of a bilinear form
69911
Does non-uniqueness of solution to 1st order ODE implies the existence of infinitely many solutions?
60810
Taylor's polynomial uniqueness proof - why are these limits inferable?
146540
Lagrange Multipler KKT condition
45682
Show that there exists a unique $v_0 \in H^1(0,1)$ such that $u(0)=\int_0^1(u'v_0'+uv_0), \forall u \in H^1(0,1)$
4989
Why are there only derivatives to the first order in the Lagrangian?
86193
Rigorous proof that $dx dy=r\ dr\ d\theta$