I’ll be speaking at the MAA Epadel Conference (March 29, near Harrisburg, PA), and to celebrate, I made two logic puzzles. Solutions, more info, and PDF versions are on my blog: https://quadratablog.blogspot.com/.../epadel-march-29th...
Rules are on the puzzles but I'll summarize here.
Fill in the grid so that:
1. Each row, column, and 3×3 square cage contains the numbers 1 through 9 exactly once.
2. Circles mean the sum of adjacent cells is 9.
3. Diamonds mean the absolute difference between adjacent cells is 2 (order does not matter).
4. If no symbol connects two adjacent cells in a cage, their sum is not 9 and their difference is not 2.
Some starting numbers are given as hints, but these puzzles actually would have unique solutions even without them.
The one with more starting clues is considerably easier than the other. Give it a try if you want a gentler challenge. Let me know if you solve either one!












