Geometric and spectral properties of causal maps

Nicolas Curien, Tom Hutchcroft, Asaf Nachmias

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


We study the random planar map obtained from a critical, finite variance, Galton- Watson plane tree by adding the horizontal connections between successive vertices at each level. This random graph is closely related to the well-known causal dynamical triangulation that was introduced by Ambjørn and Loll and has been studied extensively by physicists. We prove that the horizontal distances in the graph are smaller than the vertical distances, but only by a subpolynomial factor: The diameter of the set of vertices at level n is both o.n/ and n1-o.1/. This enables us to prove that the spectral dimension of the infinite version of the graph is almost surely equal to 2, and consequently the random walk is diffusive almost surely. We also initiate an investigation of the case in which the offspring distribution is critical and belongs to the domain of attraction of an α-stable law for α ∈ .1; 2/, for which our understanding is much less complete.

Original languageEnglish
Pages (from-to)3997-4024
Number of pages28
JournalJournal of the European Mathematical Society
Issue number12
StatePublished - 18 Aug 2020


FundersFunder number
Microsoft Research
Horizon 2020 Framework Programme740943, 676970
European Research Council
Israel Science Foundation1207/15
Tel Aviv University
Institut universitaire de FranceANR-15-CE40-0013, ANR-14-CE25-0014
Université Paris-Sud


    • Random trees
    • Random walks
    • Spectral dimension


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