arXiv subjects

Egor Lappo

Publications and source records attributed to Egor Lappo.

4 recordsLinked to original sources

arXiv2026

Quo nomine vis vocari? Random-copying, conformity, and anti-conformity in the temporal sequence of papal names

The study of cultural evolution seeks to understand the processes by which behavioral variants are chosen in human cultures over time. The selection of new popes, each of whom chooses a papal name -- typically reusing previous names in reference to previous popes -- is among the longest ongoing cultural processes taking place in a single human institution. Here, we test the papal naming sequence against predictions of models developed in population genetics and stochastic processes -- Ewens sampling theory and the Chinese restaurant process -- which in the case of papal names amount to randomly copying an existing name in proportion to its frequency, with the possibility of innovation. Although papal name choices are careful individual decisions, we find that the sequence of papal names often accords with a random-copying model, with long periods in which a model of conformity in name choices more closely fits the name sequence and other periods in which anti-conformity provides a closer fit. Hence, despite the consideration that enters into individual choices, aggregate cultural behavior in a 2000-year old human process can potentially be described with simple laws. Our methods can potentially be used to deepen quantitative analyses of conformity and anti-conformity in other cultural processes that involve discrete cultural variants.

q-bio.PE↗

arXiv2023

Cultural transmission of move choice in chess

The study of cultural evolution benefits from detailed analysis of cultural transmission in specific human domains. Chess provides a platform for understanding the transmission of knowledge due to its active community of players, precise behaviors, and long-term records of high-quality data. In this paper, we perform an analysis of chess in the context of cultural evolution, describing multiple cultural factors that affect move choice. We then build a population-level statistical model of move choice in chess, based on the Dirichlet-multinomial likelihood, to analyze cultural transmission over decades of recorded games played by leading players. For moves made in specific positions, we evaluate the relative effects of frequency-dependent bias, success bias, and prestige bias on the dynamics of move frequencies. We observe that negative frequency-dependent bias plays a role in the dynamics of certain moves, and that other moves are compatible with transmission under prestige bias or success bias. These apparent biases may reflect recent changes, namely the introduction of computer chess engines and online tournament broadcasts. Our analysis of chess provides insights into broader questions concerning how social learning biases affect cultural evolution.

physics.soc-ph↗

arXiv2022

Concordance of spatial graphs

We define smooth notions of concordance and sliceness for spatial graphs. We prove that sliceness of a spatial graph is equivalent to a condition on a set of linking numbers together with sliceness of a link associated to the graph. This generalizes the result of Taniyama for $\theta$-curves.

math.GT↗

arXiv2021

A lattice structure for ancestral configurations arising from the relationship between gene trees and species trees

To a given gene tree topology $G$ and species tree topology $S$ with leaves labeled bijectively from a fixed set $X$, one can associate a set of ancestral configurations, each of which encodes a set of gene lineages that can be found at a given node of the species tree. We introduce a lattice structure on ancestral configurations, studying the directed graphs that provide graphical representations of lattices of ancestral configurations. For a matching gene tree topology and species tree topology $G=S$, we present a method for defining the digraph of ancestral configurations from the tree topology by using iterated cartesian products of graphs. We show that a specific set of paths on the digraph of ancestral configurations is in bijection with the set of labeled histories -- a well-known phylogenetic object that enumerates possible temporal orderings of the coalescences of a tree. For each of a series of tree families, we obtain closed-form expressions for the number of labeled histories by using this bijection to count paths on associated digraphs. Finally, we prove that our lattice construction extends to nonmatching tree pairs, and we use it to characterize pairs $(G,S)$ having the maximal number of ancestral configurations for a fixed $G$. We discuss how the construction provides new methods for performing enumerations of combinatorial aspects of gene and species trees.

q-bio.PE↗