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Jul 19, 2022 at 4:54 comment added Ville Salo My reading is that they are not really making a mathematical statement about GoL, but more stating that there are no "a priori"/obvious local conservation laws. Also it seems they have only performed some simulations, so if they are making a statement, I am suspicious of it.
Jul 18, 2022 at 18:55 comment added I. J. Kennedy @VilleSalo sci-hub.se/10.1038/342780a0
Jul 18, 2022 at 14:21 comment added Ville Salo I did not find it on scihub, have to retry
Jul 18, 2022 at 13:16 comment added Mormegil @VilleSalo: FWIW, the Nature letter is on Sci-Hub, but I have no idea where/if the study itself was published.
Jul 17, 2022 at 19:41 comment added Hollis Williams @The_Sympathizer Are you asking why Noether's theorem only applies to continuous and not discrete symmetries?
Jul 17, 2022 at 11:11 comment added Ville Salo I just would've thought that's much beyond what we currently know, so I was surprised. Doesn't this rule out things like immortal creatures that survive in every context?
Jul 17, 2022 at 10:25 comment added Carlo Beenakker @VilleSalo a "locally conserved functional" relates changes in that functional on some compact region to a current through the boundaries; a formal definition is in Additive conserved quantities in discrete-time lattice dynamical systems --- I do not know of a proof that the Game of Life lacks such a functional, the paper I cite in the post states this without proof.
Jul 17, 2022 at 7:53 comment added Carlo Beenakker @The_Sympathizer --- indeed, the discretization is not the main obstacle to an application of Noether's theorem to the Game of LIfe, it's the absence of a Lagrangian.
Jul 17, 2022 at 7:52 history edited Carlo Beenakker CC BY-SA 4.0
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Jul 17, 2022 at 7:26 comment added Ville Salo Mainly, I was wondering what "it is not possible to define a locally conserved energy functional" means exactly.
Jul 17, 2022 at 7:21 comment added Ville Salo I cannot access this paper, does it contain mathematical theorems, and could you quote some relevant ones?
Jul 17, 2022 at 7:15 comment added The_Sympathizer That's interesting. But the discrete-time analogue of differentiation is the finite difference. What causes a finite-difference analogue of the theorem to fail to "go through", i.e. where does an attempt to prove it in analogous fashion to the continuous case, break?
Jul 17, 2022 at 7:10 history answered Carlo Beenakker CC BY-SA 4.0