{ "id": "1110.2163", "version": "v4", "published": "2011-10-10T19:58:16.000Z", "updated": "2014-11-13T11:32:51.000Z", "title": "Invariance principles for Galton-Watson trees conditioned on the number of leaves", "authors": [ "Igor Kortchemski" ], "comment": "46 pages, 2 figures. Published version", "journal": "Stochastic Process. Appl. 122 (2012), no. 9, 3126-3172", "doi": "10.1016/j.spa.2012.05.013", "categories": [ "math.PR" ], "abstract": "We are interested in the asymptotic behavior of critical Galton-Watson trees whose offspring distribution may have infinite variance, which are conditioned on having a large fixed number of leaves. We first find an asymptotic estimate for the probability of a Galton-Watson tree having $n$ leaves. Secondly, we let $t_n$ be a critical Galton-Watson tree whose offspring distribution is in the domain of attraction of a stable law, and conditioned on having exactly $n$ leaves. We show that the rescaled Lukasiewicz path and contour function of $t_n$ converge respectively to $X^{exc}$ and $H^{exc}$, where $X^{exc}$ is the normalized excursion of a strictly stable spectrally positive L\\'evy process and $H^{exc}$ is its associated continuous-time height function. As an application, we investigate the distribution of the maximum degree in a critical Galton-Watson tree conditioned on having a large number of leaves. We also explain how these results can be generalized to the case of Galton-Watson trees which are conditioned on having a large fixed number of vertices with degree in a given set, thus extending results obtained by Aldous, Duquesne and Rizzolo.", "revisions": [ { "version": "v3", "updated": "2012-05-22T07:09:50.000Z", "title": "Invariance principles for Galton-Watson trees conditioned on their number of leaves", "abstract": "We are interested in the asymptotic behavior of critical Galton-Watson trees whose offspring distribution may have infinite variance, which are conditioned on having a large fixed number of leaves. We first find an asymptotic estimate for the probability of a Galton-Watson tree having $n$ leaves. Secondly, we let $\\t_n$ be a critical Galton-Watson tree whose offspring distribution is in the domain of attraction of a stable law, and conditioned on having exactly $n$ leaves. We show that the rescaled Lukasiewicz path and contour function of $\\t_n$ converge respectively to $\\X$ and $\\H$, where $\\X$ is the normalized excursion of a strictly stable spectrally positive L\\'evy process and $\\H$ is its associated continuous-time height function. As an application, we investigate the distribution of the maximum degree in a critical Galton-Watson tree conditioned on having a large number of leaves. We also explain how these results can be generalized to the case of Galton-Watson trees which are conditioned on having a large fixed number of vertices with degree in a given set, thus extending results obtained by Aldous, Duquesne and Rizzolo.", "comment": "46 pages, 2 figures. Final version: title changed, minor corrections. To appear in Stochastic Processes and their Applications. arXiv admin note: text overlap with arXiv:1109.4138", "journal": null, "doi": null }, { "version": "v4", "updated": "2014-11-13T11:32:51.000Z" } ], "analyses": { "keywords": [ "galton-watson trees", "invariance principles", "critical galton-watson tree", "spectrally positive levy process", "stable spectrally positive levy" ], "tags": [ "journal article" ], "note": { "typesetting": "TeX", "pages": 46, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2011arXiv1110.2163K" } } }