All examples in this Problem are groups of 3 dots.

Any example where 2 adjacent dots have the same height would be ambiguously sorted.

Reading from right to left in the first box on the left hand side: the 2nd dot is higher than the 1st, and the 3rd is higher than the 2nd, so the sequence of dots is strictly increasing in height.

Point sequence that is increasing or decreasing in height vs. point sequence that alternates in height

All examples in this Problem are groups of 3 dots.

Any example where 2 adjacent dots have the same height would be ambiguously sorted.

Reading from left to right in the first box on the left hand side, the 2nd dot is higher than the 1st, and the 3rd is higher than the 2nd, so the sequence of dots is strictly increasing in height.

Leo Crabbe

Dots increasing in y position from left-to-right OR right-to-left vs. dots not sorted by y position along x axis

Dots increasing in y position from left-to-right OR right-to-left vs. dots with un-sorted y position along x axis

Reading from left to right in the first box on the left hand side: the 2nd dot is lower than the 1st, and the 3rd is lower than the 2nd, so the sequence of dots is strictly decreasing in height.

Point sequence that is increasing OR decreasing in height vs. point sequence that alternates in height

Reading from left to right in the first box on the left hand side: the 2nd dot is higher than the 1st, and the 3rd is higher than the 2nd, so the sequence of dots is strictly increasing in height.