Is the following sentence correct?
"This limits the algorithm to relationships the user already knows exist."
As a non-native English speaker I am struggling to determine which verbs should be plural and which should be singular.
Where I am having difficulty is with the "exist(s)" and "know(s)". How I argued was that "relationships" is plural so I put it with plural "exist" and the "user" is singular so it goes with singular "knows".
But I'm not sure weather this is right or weather I must apply the "user" singular-ness to both "knows exists" because it is closer to it? I am really confusing myself.
(I know starting the sentence with "this" seems confusing but in context of the thesis it is part of it makes sense)