Vol XXIX 2019 – 2020

Vol XXIX 2019 – 2020

Geombinatorics

A quarterly journal on open problems of combinatorial and discrete geometry and related areas.

July 2019 – April 2020

Issue 1   Issue 2   Issue 3    Issue 4 


Issue 1 (July 2019)


CONTENTS XXIX (1)

Editor’s Page………………….………………………………..….4

New Essays

  • Polyominoes with maximally many holes……………………………..5

by Matthew Kahle and Érika Roldán    

  • Generalizations of the No-Three-in-a-Line Problem………….…21

by Dustin LaFollette and Anant Godbole

  • The Smallest Art Gallery Not Guarded by Every Third
    Vertex……….…………………………………………………………………24

by Ralph Morrison     

 

  • The International Mathematics Union Abacus Medal……………33

       by Alexander Soifer

  • On a Geometric Proof of Sums of Powers…………………………………………….37

by Joseph Zaks

 

       Recent Books…………………………………………….…42

 

Subscription Form…………….……….………………………43


Issue 2  (October 2019)


Editor’s Page………………….…………………………………48

New Essays

  • Coloring Distance Graphs on the Integers…………………………..49

by Matthew Ellison, Joseph Johnson

  

  • Fission of Halving Edges Graphs……………………………..…56

by Tanya Khovanova and Dai Yang

  • 4-Regular Planar Unit Triangle Graphs without Additional Triangles………..…………………………..…72

by Mike Winkler, Peter Dinkelacker,

and Stefan Vogel

 

  • Dynamic Triggering of Earthquakes: Symmetry-Based Geometric Analysis……………………………78

by Laxman Bokati, Richard Alfaro,

Aaron Velasco, and Vladik Kreinovich

 

       Recent Books…………………………………………….…89

 

Subscription Form…………….……….………………………91


Issue 3 (January 2020)


Editor’s Page………………….…………………………………96

New Essays

  • A 6-chromatic two-distance graph in the plane…………………..97

by Geoffery Exoo, Dan Ismailescu

  

  • Nonlinear Mechanical Properties of Road Pavements:
    Geometric Symmetries Explain the Empirical Difference
    Between Roads Built on Clay vs. Granular Soils……………………………………………………………………………..…104

by Afshin Gholamy, Vladik Kreinovich

  • A Small 6-Chromatic Two-Distance Graph in the Plane……………………………………………..…………………………..…111

by Jaan Parts

  • A 3-Regular Matchstick Graph of Girth 5
    Consisting of 54 Vertices…………………………………………………116

by Mike Winkler, Peter Dinkelacker, and Stefan Vogel

  • On the Cyclic Van der Waerden Number Wc(4; 2) ………………………………………………………………………………………122

by Carson Wood

       Recent Books…………………………………………….…130

 

Subscription Form…………….……….………………………131


Issue 4 (April 2020)