01
Apply both coordinate comparisons to each point
Under the closed rule, x must be at least two and at most six, while y must be at least one and at most four. P satisfies both conditions and lies inside. Q is included on the right edge, and R is included on the top-left corner. S fails the horizontal condition because its x coordinate is one, so it is outside even though its y coordinate is within range. Both axes must satisfy their conditions. Checking only the vertical range would incorrectly include S and conceal the purpose of the rectangular region.
02
Change only the upper-bound inclusion rule
Under the half-open rule, x is at least two but less than six, and y is at least one but less than four. P remains included. Q is now excluded because its x coordinate equals six. R is excluded because its y coordinate equals four, even though its x coordinate equals the included left boundary. S remains outside. The included set changes from P, Q and R to P alone. These differences follow from the declared comparisons; they do not indicate that any point moved or that one of the diagrams was drawn incorrectly.
03
Use adjacent cells to explain unique assignment
Add a second half-open rectangle whose horizontal range starts at six and ends before ten, with the same vertical range from one inclusive to four exclusive. Q at (6,2) belongs to this second rectangle and not the first. Their shared vertical boundary therefore has a single assignment for that point. A worksheet should save both bounds, the inclusion convention, point coordinates and the comparison that determines each result. Outer edges of a larger partition may need an additional policy. State that policy separately rather than assuming the example has already assigned every possible position.