Swiss Cheese

Standard sudoku rules apply: The digits 1 through 9 appear in every row, column, and box. Fog: Part of the grid is covered with fog. As correct digits are placed, the fog will clear from surrounding cells. Arrows: Digits along an arrow must sum to the number indicated in the circle from which the arrow emerges. Digits may repeat along arrows if allowed by other rules. All arrows in this puzzle have three digits along the shaft. No arrow shaft has a bend of 90 degrees or less. Arrows do not intersect along shafts. Kropki pairs: Digits in cells separated by a black dot are in a 2:1 ratio. Digits in cells separated by a white dot are consecutive. Not all dots are necessarily given.