Normal sudoku rules apply. There are nine doubler and nine halver cells in the grid. Place one doubler and one halver in every row, column and box such that doublers and halvers cannot share a cell, and each digit from 1-9 appears once in a doubler cell and once in a halver cell. A doubler cell's value counts as double its digit while a halver cell's value counts as half its digit. Values on a grey palindrome line read the same forwards and backwards. Box borders divide each blue line into segments whose values have the same sum. Each inequality symbol ‘points’ to the smaller value of the two joined cells.