Memorial for Mari-Jo P. Ruiz ---A Colleague and Friend in Art and Math.- Mari-Jo P. Ruiz: Mathematician, Mentor, Leader.- Mari-Jo P. Ruiz and Graph Theory.- This Game Is Not Going To Analyze Itself.- Unveil the secret hidden in the Haberdasher's puzzle -Survey on Reversibility.

- Multipartite Ramsey Numbers of Double Stars.- Counting $2$-factors of $4$-regular bipartite graphs is $\#P$-complete.- The Two-Squirrel Problem and Its Relatives.- A Subquadratic Time Algorithm for the Weighted k-Center Problem on Cactus Graphs.- Complexity of Solo Chess with Unlimited Moves.- Stars in Forbidden Triples Generating a Finite Set of 4-connected Graphs.- Geodesic Paths Passing Through All Faces on A Polyhedron.- Partitions of complete twisted graphs into plane spanning trees.

- The Edge-Intersection Graph of Induced Paths in a Graph.- All Paths Lead to Rome.- Numerically balanced dice on convex isohedra.- Nonrealizable Planar and Spherical Occlusion Diagrams.- Maximum numbers of rigid faces and edges in continuous flattening of regular polyhedra.- Find Routes on a Doughnut.- Previous Player's Positions in Impartial Three-Dimensional Chocolate-Bar Games with Constrained Chocolate Size.- Algorithms for Burning Schedule Reconfiguration Problem on Path Forests.

- Continuous Folding of the Surface of a Hypercube onto one of its Facets.- Weights of Convex Quadrilaterals and Empty Triangles in Weighted Point Sets.- New Formulation for Coloring Circle Graphs.- On the Computational Complexity of Pushing Machine.