1. Parametric rigidity of the Hopf bifurcation up to analytic conjugacy

   • Waldo Arriagada

   OriginalPaper 21 June 2021 Pages: 1 - 17

   

2. The algebraic and geometric classification of nilpotent right alternative algebras

   • Nurlan Ismailov
   • Ivan Kaygorodov
   • Manat Mustafa

   OriginalPaper 14 June 2021 Pages: 18 - 30

3. Colouring finite products

   • Stevo Todorcevic

   OriginalPaper 07 June 2021 Pages: 31 - 36

4. Sumsets of Wythoff sequences, Fibonacci representation, and beyond

   • Jeffrey Shallit

   OriginalPaper 01 July 2021 Pages: 37 - 46

   

5. Existence of an uncountable tower of Borel subgroups between the Prüfer group and the s-characterized group

   • Pratulananda Das
   • Kumardipta Bose

   OriginalPaper 30 June 2021 Pages: 47 - 55

6. On open books for nonorientable 3-manifolds

   • Burak Ozbagci

   OriginalPaper 29 June 2021 Pages: 56 - 69

   

7. The inverse Kakeya problem

   • Sergio Cabello
   • Otfried Cheong
   • Michael Gene Dobbins

   OriginalPaper 25 June 2021 Pages: 70 - 75

8. r-Almost Newton–Ricci solitons on Legendrian submanifolds of Sasakian space forms

   • Uday Chand De
   • Mohammad Danish Siddiqi
   • Sudhakar K. Chaubey

   OriginalPaper 28 June 2021 Pages: 76 - 88

9. Arithmetic properties of polynomial solutions of the Diophantine equation \(P(x)x^{n+1}+Q(x)(x+1)^{n+1}=1\)

   • Karl Dilcher
   • Maciej Ulas

   OriginalPaper Open access 29 April 2021 Pages: 89 - 118

10. The sum of reciprocals of least common multiples

    • Jin-Hui Fang
    • Jie Ma

    OriginalPaper 29 June 2021 Pages: 119 - 124

11. On the intersection of k-Lucas sequences and some binary sequences

    • Salah Eddine Rihane
    • Alain Togbé

    OriginalPaper 12 June 2021 Pages: 125 - 145

12. Existence of solutions for nonlocal elliptic systems involving p(x)-Laplace operator

    • S. Firouzi
    • G. A. Afrouzi

    OriginalPaper 12 July 2021 Pages: 146 - 158