The Prime Directive
(Published on 1. February 2023, 12:00 by Tobias Brixner)
Puzzle links: Play on CTC SudokuPad (with solution check) or f-puzzles.
Rules: Normal Sudoku rules apply, i.e., place the numbers 1-9 once each into each row, column, and 3×3 box.
Place one prime number into each cage without repeats. Two-cell cages contain two-digit numbers written in ordinary notation from left to right.
Along a purple line, adjacent cells differ by a prime number. That difference is the same throughout one specific line. Digits may repeat on a purple line if allowed by other rules.
For reference, all the prime numbers from 1 to 100 are: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.
Background: There are some prime-positioning puzzles published on Logic Masters. Most closely related to the present one are Minister of Primes by Mountainfarmer in which some two-digit prime numbers are notated horizontally, others vertically, and one diagonally; Prime Real Estate by Will Power in which most two-digit primes are notated horizontally but one vertically; and Sudoku Prime by GrizzledStoat in which all two-digit primes are notated horizontally but the grid containes fewer of them.
My goal was to find a grid containing primes in the usual left-to-right notation only. Further, I wanted to employ clues without explicit numbers only. In the setting process, it was quite challenging (for me) to assemble everything without breaking the puzzle (and then also to lay out a solve path).
The title is a pun on The Prime Directive from Star Trek which is "a guiding principle of Starfleet that prohibits its members from interfering with the natural development of alien civilizations". In the puzzle, the "prime directive" does not just signify "primary" as it does in Star Trek but of course refers to prime numbers, i.e., "directing" you how to place them in the grid.
Fun fact: The release date of this puzzle is a prime number (20230201) when written in the form YYYYMMDD.
Solution code: Column 1 (Digits from top to bottom without space)
Comments
on 5. February 2023, 02:37 by damasosos92
A very good one! Thank you!
on 1. February 2023, 18:05 by dinocat
Absolutely lovely! Everything just flows along clue by clue
