Sangaku Journal of Mathematics Published by the Association for the Development of Education, Sofia, Bulgaria About this Journal   |   Editorial Board  |   Instructions for Authors   |   Review Process   |   Links ISSN 2534-9562 Editors-in Chief: Hiroshi Okumura, Professor, Ph.D. Takahanadai Maebashi Gunma, Japan e-mail: hokmr@yandex.com Sava Grozdev, Professor, DSc, Association for the Development of Education, Sofia, Bulgaria e-mail: sava.grozdev@gmail.com Volume 8 (2024) J. Marshall Unger, Notes on the six-segment theorem, pp.1-8. Volume 7 (2023) Hiroshi Okumura, A rare sangaku problem involving three congruent circles, pp.1-8. Hiroshi Okumura, Problems 2023-1, pp.9-12. Paris Pamfilos, Note on a sangaku like construction of X(55), pp. 13-15. Vishwesh Ravi Shrimali, Solution for Problems 2 and 3 of Problems 2023-1, pp. 16-19. Kousik Sett, Solution for Problems 2 and 3 of Problems 2023-1 by Vishwesh Ravi Shrimali (ERRATA), p. 20. Ercole Suppa and Marian Cucoanes, Solution of Problems 2023-1-6, pp. 21-28. Hiroshi Okumura and Kousik Sett, The arbelos in Wasan geometry: the Aida arbelos and Problem 2023-1-5, pp. 29-31. Hiroshi Okumura, A configuration arising from Problem 2023-1-1, pp. 32-34. Kai-Uwe Ekrutt and Floor van Lamoen, Further notes on Tamura’s problem in the general arbelos, pp. 35-41. Paris Pamfilos, On a sangaku like configuration involving a triangle and three congruent circles, pp. 42-53. Ercole Suppa and Stanley Rabinowitz, A triad of circles associated with a triangle, pp. 54-70. Stanley Rabinowitz and Ercole Suppa, Properties of Ajima circles, pp. 71-145. Hiroshi Okumura and Dao Thanh Oai, Twin circles of a generalized arbelos with division by zero 1/0=0, pp. 146-150. Kousik Sett, Relationships between radii in a six-circle configuration, pp. 151-161. Volume 6 (2022) Hiroshi Okumura, A note on a generalization of a five circle problem, pp.1-2. Hiroshi Okumura, A note on a generalization of a five circle problem: Part 2, pp.3-5. Hiroshi Okumura, A note on a generalization of a five circle problem: Part 3, pp.6-8. Li Ting Hon Stanford, A configuration involving a square and two equilateral triangles, pp.9-12. Hiroshi Okumura, Some generalizations of five circle problems, pp.13-18. Hiroshi Okumura, A note on circles touching two circles in a Pappus chain, pp.19-22. Hiroshi Okumura, A note on circles touching two circles in a Pappus chain: Part 2, pp.23-25. Kousik Sett, A note on a chain of contact circles inside a circular segment, pp.26-30. Kousik Sett, An alternative proof of the Japanese theorem, pp.31-33. Li Ting Hon Stanford, A simple method to explore the relationships between six areas, pp.34-36. Hiroshi Okumura, A note on circles touching two circles in a Pappus chain: Part 3, pp.37-40. J. Marshall Unger, A response to an open question of Rabinowitz, pp.41-44. Volume 5 (2021) Hiroshi Okumura, The arbelos in Wasan geometry, the inscribed semicircle in the arbelos, pp.1-8. Li Ting Hon Stanford, Ellipses inscribed in trapezoids and solutions to 2020-1 Problems 1 and 2, pp.9-13. Hiroshi Okumura, The arbelos in Wasan geometry: Totsuka's problem (Problem 2017-3-6), pp.14-18. Kousik Sett, A constant associated with Ikeda's theorem, pp.19-23. Hiroshi Okumura, The arbelos in Wasan geometry: Saitoh's problem, pp.24-31. Hiroshi Okumura, The arbelos in Wasan geometry: Atsumi's problem with division by zero calculus, pp.32-38. Hiroshi Okumura, The arbelos in Wasan geometry: a problem in Sangaku Shōsen, pp.39-42. J. Marshall Unger, How Wasanka did integration: The case of the Japanese wedge, pp.43-55. Volume 4 (2020) Hiroshi Okumura, A four circle problem and division by zero, pp.1-8. Stanley Rabinowitz, Relationships between circles inscribed in triangles and related curvilinear triangles, pp.9-27. Hiroshi Okumura and Ercole Suppa, A remark on an Archimedean square of a triangle associated with an arbelos, pp.28-30. Hiroshi Okumura, Ootoba's Archimedean circles of the collinear arbelos, pp.31-35. Problems 2020-1, pp.36-40. Géry Huvent, Solution to Problem 2019-4, pp.41-44. Hiroshi Okumura, A generalization of Problem 2019-4 and division by zero, pp.45-52. Géry Huvent, Solution to Problem 2020-1 Problem 9, pp.53-60. Hiroshi Okumura, Non-Archimedean congruent circles in Tenzan Tebikigusa Furoku, pp.61-68. Abdilkadir Altintas, Problem 2020-2, p.69. Kousik Sett, Solution to Problem 2020-2, pp.70-72. Hiroshi Okumura, Solution to Problem 2017-1-6 with division by zero, pp.73-76. Stanley Rabinowitz, Relationships between six areas, pp.77-83. Supplementary Material. sixAreas.nb Li Ting Hon Stanford, A note on a sangaku problem involving the Steiner ellipse, pp.84-85. Emmanuel Antonio Jose Garcia, Three Archimedean circles arising from equilateral triangles, pp.86-87. Volume 3 (2019) Le Viet An and Emmanuel Antonio Jose Garcia, A pair of Archimedean incircles, pp.1-2. Paul Yiu and Xiao-Dong Zhang, Diagram 29 in the appendix of Yojutsu Shindai, pp.3-11. Hiroshi Okumura, A note on the arbelos in Wasan geometry, a problem in Sampo Tenzan Tebikigusa Furoku, pp.12-14. Hiroshi Okumura, A note on the arbelos in Wasan geometry, Satoh’s problem, pp.15-16. Problems 2019-1, pp.17-18. Hiroshi Okumura, A note on the arbelos in Wasan geometry, Matsuda’s problem, pp.19-23. Hiroshi Okumura, Problems 2019-2, pp.24-25. Problems 2019-3, pp.26-28. Kyouichi Gowa and Chieko Miyota, A sangaku problem involving four circles in a rectangle, pp.29-31. Waldemar Pompe, On a sangaku problem involving the incircles in a square tiling: Solutions to Problems 2019-2, pp.32-35. Tsutomu Matsuura, Hiroshi Okumura, and Saburou Saitoh, Division by zero calculus and Pompe's theorem, pp.36-40. Hiroshi Okumura, Arbeloi determined by a chord and solutions to Problems 2017-3-8 and 2019-3-4, pp.41-50. Stanley Rabinowitz, Relationships between six incircles, pp.51-66. Supplementary Material. Sixincircles.zip Hiroshi Okumura, A characterization of the golden arbelos involving an Archimedean circle, pp.67-71. Problems 2019-4, pp.72-72. Stanley Rabinowitz, Relationships between six excircles, pp.73-90. Supplementary Material. Sixexcircles.zip Hiroshi Okumura, The arbelos in Wasan geometry: Ootoba's problem and Archimedean circles, pp.91-97. Stanley Rabinowitz, Relationships between six circumcircles, pp.98-105. Stanley Rabinowitz, More relationships between six circles, pp.106-118. Hiroshi Okumura, Remarks on Archimedean circles of Nagata and Ootoba, pp.119-122. Hiroshi Okumura, Remarks on a problem involving four circles in a parallelogram, pp.123-125. Volume 2 (2018) Giovanni Lucca, A note on a Pappus sangaku problem and a Family of Integer Sequences, pp.1-2. Hiroshi Okumura, A note on a problem involving a square in a curvilinear triangle, pp.3-5. Problems 2018-1, p.6. Abdilkadir Altintas, Problems 2018-2, p.7. Hiroshi Okumura, A note on an isosceles triangle containing a square and three congruent circles, pp.8-10. Abdilkadir Altintas and Hiroshi Okumura, A note on Pappus chain and a collinear theorem, pp. 11-12. Viera Čerňanová, Solution to 2018-1 Problem 2, pp.13-14. Viera Čerňanová, Solution to 2018-1 Problem 1, pp.15-16. Hiroshi Okumura, Solution to 2017-3 Problem 5, pp.17-21. Jana Fialová, Solution to 2018-2 Problem 1, pp.22-23. Hiroshi Okumura, Solution to the problem proposed in "Solution to 2017-3 Problem 5", pp.24-26. Hiroshi Okumura, Solution to 2017-1 Problem 4 with division by zero, pp.27-30. Giovanni Lucca, Integer sequences and circle chains inside a tangential quadrilateral, pp.31-40. Problems 2018-3, pp.41-42. Hiroshi Kinoshita, An unsolved problem in the Yamaguchi's travell diary, pp.43-53. The paper is reprinted from "Shotoh Sugaku", Volume 70 (2012) pp. 32-36 with permission from the publisher along with a supplementary Appendix. Hiroshi Okumura, Solution to Problem 2018-3-2, pp.54-56. Hiroshi Okumura and Saburou Saitoh, Wasan Geometry and Division by Zero Calculus, pp.57-73. Li Ting Hon Stanford, Solution to 2017-3 Problem 3, pp.74-75. Jana Fialová, Inscribed rectangles in a kite and a solution to 2017-1 Problem 5, pp.76-82. Volume 1 (2017) Hiroshi Okumura, Japanese mathematics, pp.1-6. The paper is reprinted from "Symmetry: Culture and Science",Volume 12 (1-2) 79-86 (2001) with permission from the publisher. Problems 2017-1, pp.7-10. Problems 2017-2, pp.11-12. Francisco Javier García Capitán, Solution to 2017-1 Problem 1, pp.13-15. Yasuo Kanai and Hiroshi Okumura, A three tangent congruent circle problem, pp.16-20. Supplementary material: animation.gif Problems 2017-3, pp.21-23. Hiroshi Okumura, Configurations of congruent circles on a line, pp.24-34. Hiroshi Okumura, Theorems on two congruent circles on a line, pp.35-38. Hiroshi Okumura, A note on the problems involving congruent circles in Tenzan Kaitei, pp.39-41. Hiroshi Okumura, Haga's theorems in paper folding and related theorems in Wasan geometry Part 1, pp.42-56.