FA-94343 / Exam timetabling constraints / Member archive

Repeated enrolment row reported as an exam clash · case 03

A student enrolled twice in the same exam appears to have two exams in one period.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

enrol rows [student, exam] (may repeat), period maps scheduled exams to a period, xlist groups cross-listed exams that are one physical paper (canonical name = smallest id in the group). A clash is a student with two or more distinct canonical papers in one period; unscheduled exams are ignored. Return [student, period, sorted papers] ordered by student then period.

Why this case matters

Clash detection is the primary hard constraint of exam timetabling; duplicate enrolments and cross-listing are the usual sources of false clashes.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: duplicate enrolment 1	`[["s2", 0, ["ECON150", "ECON150"]], ["s3", 0, ["ECON150", "MATH101H"]]]`	`[["s3", 0, ["ECON150", "MATH101H"]]]`	Failed

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