# The Sunflower Lemma of Erdős and Rado

 Title: The Sunflower Lemma of Erdős and Rado Author: René Thiemann (rene /dot/ thiemann /at/ uibk /dot/ ac /dot/ at) Submission date: 2021-02-25 Abstract: We formally define sunflowers and provide a formalization of the sunflower lemma of Erdős and Rado: whenever a set of size-k-sets has a larger cardinality than (r - 1)k · k!, then it contains a sunflower of cardinality r. BibTeX: @article{Sunflowers-AFP, author = {René Thiemann}, title = {The Sunflower Lemma of Erdős and Rado}, journal = {Archive of Formal Proofs}, month = feb, year = 2021, note = {\url{https://isa-afp.org/entries/Sunflowers.html}, Formal proof development}, ISSN = {2150-914x}, } License: BSD License