FA-15093 / Numerics / Member archive
Lehmer permutation rank: unused alphabet initialization · case 03
The exact lehmer permutation rank result violates the stated contract at unused alphabet initialization.
Case contract
Input permutation of 0..n-1 with n<=7; return zero-based lexicographic rank.
Why this case matters
Exact discrete arithmetic with observable algorithmic state; no floating point approximation is used.
One recorded failure
Sample boundary fixtureThis sample comes from the broken implementation of a controlled reproducer.
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| explicit oracle 0 | null | 1 | Failed |
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