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2009.02586

Typical ground states for large sets of interactions

Aernout van Enter, Jacek Miękisz

correctmedium confidence
Category
Not specified
Journal tier
Note/Short/Other
Processed
Sep 28, 2025, 12:55 AM

Audit review

The paper works in the interaction space B0, canonically identified with C(Ω), and uses Morris’ theorem to pull generic properties of invariant measures (weakly mixing, not mixing, singular spectrum, non-Gibbs) to a dense Gδ set of potentials. This is explicitly stated in Section 3 and Corollary 2, with discussion in the abstract and introduction . The candidate’s contradiction hinges on transferring a residual periodic-maximizer statement from the Lipschitz class on the one-sided shift to an open dense set in C(Ω) for the two-sided shift. That density step fails: functions depending only on nonnegative coordinates (lifted via π) are not dense in C(Ω), so the proposed approximation of an arbitrary U ∈ C(Ω) by V = W∘π is generally impossible. Hence the claimed open dense subset O ⊂ C(Ω) with periodic ground states cannot be established. The paper itself even acknowledges that in smaller/regularity-restricted spaces (e.g., Lipschitz in d=1) periodic ground states can be generic, but stresses that its generic results are for C(Ω) (B0) .

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} note/short/other

\textbf{Justification:}

A concise and essentially correct note: leveraging Morris’ theorem to deduce that generic continuous interactions have ground states that are weakly mixing, not mixing, with singular spectrum, and not Gibbs. The argument is sound and well-motivated. Clarifying references for the genericity of weak mixing (and the meagreness of mixing) among invariant measures under the fixed shift action would remove possible ambiguity. The contrast with smaller interaction spaces where periodicity can be generic is helpful and accurate.