Sprouts 2025 Morning Talks

Sprouts 2025 was today!  In recent years, we have included early morning talks for presenters who are in so far away of a time zone that they should be asleep during our normal talks.  (At this point, this just means presenters from Asia... and one who couldn't attend later in the day.)  Even at the early hour we started, Japan is 13 hours ahead of us, so it was already quite late in the evening for them.  This year we had a record five talks during that morning session!  Here are my (spotty) summaries of those talks. 

 

Akshat Patodia & Parth Sarda: "Blippers and Flippers"

Parth and Akshat did a team talk describing two games: Blippers and Flippers.  These are inspired by generalizations of Toads and Frogs that parameterize the different allowed distances of moves and whether you can jump pieces of your own team.  Blippers and Flippers are played on 2-D grids using black and white stones instead of the usual amphibians.  Those stones are placed and removed based on rules for orthogonally-connected groups.  They were able to find some loopy positions on strips in Flippers.  

Hiyu Inoue: "On Ending Partizan Subtraction Nim"

Ending Partizan Subtraction Nim is a game where both players have the same moves (subtraction set) but the winning conditions are different.  E.g.: Left wins if there are even tokens when play reaches the terminal position, but Right wins if there are odd tokens.  This seems like a pretty evenly-biased rule, but Hiyu showed that even on subtraction set {2,3}, L shows up as an outcome class surprisingly more often then R.  This trend continues with many other subtraction sets that Hiyu studied!  He proved this is the case using a strategy-stealing argument.

Harman Agrawal: "QuadroCount: A Combinatorial Game"

Harman presented the game she's been studying: QuadroCount.  She implemented a playable version of the game online.  Each turn consists of moving one of that player's pieces in a way that lowers the "score".  The score is measured as the total size of all rectangles with each pair of opposing color stones, the "ola": OverLapping Area.  Harman has found new terminal positions.  She refers to some of them as Nash Equilibria positions because although it seems like moves should be available, all pieces are locked.  She also provided some open problems about other potential terminal positions. 

Melanie Gauthier: "Snort Strategies on Triangular Grid Graphs"

Melanie covered the basics of combinatorial games and, in particular, placement games, then described Snort.  She uses tinting to simplify diagrams during analysis (which is something Craig and I have been using in Col).  She studied winnability on initially-uncolored graphs.  She used the one-hand-tied principle to break apart triangular grid graphs after a move.  She found a ton of long graphs with two and three rows to be in N.

Kouta Kawakami: "New Rulesets and their Transfinite Grundy Values"

Kouta talked about extending nimbers by including transfinite Grundy values.  These can occur in non-loopy games that don't end in finite moves.  For example, on a Nim variant on lists where you have to remove from one pile, but then can simultaneously add to another pile with a higher index.  This yields transfinite G-values, which Kouta was able to find for instances of this game.  He also used transfinite numbers to analyze a separate single-heap non-finite game.