Each stone can have 2 lines radiating from its centre, not 3.
* - no clues must be contradicted (highlight clue itself in error if so)
* - if there is a closed loop it must include every line segment laid
* - if there's a smaller closed loop then highlight whole loop as error
- * - no square must have more than 3 lines radiating from centre point
+ * - no square must have more than 2 lines radiating from centre point
* (highlight all lines in that square as error if so)
*/