1. Hyers–Ulam stability for quantum equations

   • Douglas R. Anderson
   • Masakazu Onitsuka

   OriginalPaper 25 June 2020 Pages: 201 - 214

2. On the total and strong version for Roman dominating functions in graphs

   • S. Nazari-Moghaddam
   • M. Soroudi
   • I. G. Yero

   OriginalPaper 28 January 2021 Pages: 215 - 236

   

3. A probabilistic method of solving Lobachevsky’s functional equation

   • Michael Mania

   OriginalPaper 25 March 2020 Pages: 237 - 243

4. A fixed point theorem for a system of Pachpatte operator equations

   • Erdal Karapınar
   • Ali Öztürk
   • Vladimir Rakočević

   OriginalPaper 14 May 2020 Pages: 245 - 254

5. Symmetric spectral synthesis

   • Eszter Gselmann
   • László Székelyhidi

   OriginalPaper Open access 23 December 2020 Pages: 255 - 279

6. The small dimension lemma and d’Alembert’s equation on semigroups

   • Henrik Stetkær

   OriginalPaper 20 August 2020 Pages: 281 - 299

7. On the Cauchy difference of functions bounded modulo \(\mathbb {Z}\) on “large” sets

   • Eliza Jabłońska

   OriginalPaper Open access 19 August 2020 Pages: 301 - 308

8. A note on the g-angle between subspaces of a normed space

   • Muhammad Nur
   • Hendra Gunawan

   OriginalPaper 28 July 2020 Pages: 309 - 318

9. The chromatic number of triangle-free and broom-free graphs in terms of the number of vertices

   • Naoki Matsumoto
   • Minako Tanaka

   OriginalPaper 27 October 2020 Pages: 319 - 328

   

10. On the packing coloring of base-3 Sierpiński graphs and H-graphs

    • Fei Deng
    • Zehui Shao
    • Aleksander Vesel

    Manuscript 01 September 2020 Pages: 329 - 341

    

11. Continuity of operators intertwining with translation operators on hypergroups

    • Vishvesh Kumar
    • Ritumoni Sarma

    OriginalPaper 14 August 2020 Pages: 343 - 349

12. The weak core inverse

    • D. E. Ferreyra
    • F. E. Levis
    • N. Thome

    OriginalPaper 27 August 2020 Pages: 351 - 373

13. On increasing iteration semigroup of Jensen set-valued functions

    • Masoumeh Aghajani

    OriginalPaper 21 February 2021 Pages: 375 - 382

14. Some trigonometric functional equations on monoids generated by their squares

    • Bruce Ebanks

    OriginalPaper 19 June 2020 Pages: 383 - 391

15. Undirecting membership in models of Anti-Foundation

    • Bea Adam-Day
    • Peter J. Cameron

    OriginalPaper Open access 18 November 2020 Pages: 393 - 400