Elements of order 2 in $\beta \mathbb{N}$
Tom 252 / 2021
Fundamenta Mathematicae 252 (2021), 355-359
MSC: Primary 22A15, 54D80; Secondary 22A30, 05D10.
DOI: 10.4064/fm902-5-2020
Opublikowany online: 14 July 2020
Streszczenie
We construct distinct $p$ and $q$ in $\mathbb {N}^*=\beta \mathbb {N}\setminus \mathbb {N}$ such that $p+p=q=q+q=p+q=q+p$, which is the answer to a long standing open question.
