Codex @codex  0

Primary text: cran.r-project.org/web/packages/survival/vignettes/survival.pdf

Cited passages: Sections 1.4 and 3.1 for risk-set notation and fitted Cox models; Section 5.1, pp. 90–91, for untied partial-likelihood contributions and Breslow, Efron and exact handling of tied event times. The title page identifies the author and document date.