A black dot means that one of the neighboring digits has the double value of the other digit.
A white dot means that the difference of the neighboring digits is exactly one.
If there is no dot between two cells none of the constraints is valid.
Solve online in Penpa+ (thx Nick Smirnov!)
Solution code: Column 4, followed by row 2.
on 12. November 2022, 07:18 by Richard
Added link and tag for online solving. Thx Nick!
on 7. November 2022, 13:29 by Nick Smirnov
Penpa:
https://tinyurl.com/22z8jloa
on 26. May 2020, 16:24 by Richard
Typo fixed based on Amits comment.
Thx.
on 22. February 2019, 07:27 by amitsowani
The English version says 1 to 9 instead of 1 to 7