FA-94685 / Exam timetabling constraints / Member archive

Duplicate enrolment rows inflate conflict counts · case 05

A repeated row creates a self-conflict and double counts the student's pairs.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

enrol rows [student, exam] (may repeat). For every unordered pair of distinct exams (a < b) count the students enrolled in both. Return [a, b, count] rows sorted, omitting zero counts.

Why this case matters

The conflict matrix is the input to every exam timetabling algorithm; count errors silently change weights.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression: distinct enrolments 1	`[["BIO130", "HIST140", 1], ["BIO130", "PHYS110", 1], ["CHEM120", "ECON150", 1], ["CHEM120", "HIST140", 1], ["ECON150", "HIST140", 1], ["HIST140", "MATH101", 2], ["HIST140", "PHYS110", 2], ["MATH101", "MATH101", 1], ["MATH101", "PHYS110", 2]]`	`[["BIO130", "HIST140", 1], ["BIO130", "PHYS110", 1], ["CHEM120", "ECON150", 1], ["CHEM120", "HIST140", 1], ["ECON150", "HIST140", 1], ["HIST140", "MATH101", 1], ["HIST140", "PHYS110", 2], ["MATH101", "PHYS110", 1]]`	Failed

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