Understand the failure.
Verify the repair.
Small, reproducible software failures. The broken implementation, the fix that didn’t work, and the one that passed—preserved together.
Explore the cases ↓How results are verified ↗WHAT THE ARCHIVE CONTAINS
100840 executable cases. 20168 are open.
Every case records the implementation that fails, the fix that did not work, and the repair that passed its checks—with recorded outputs and source hashes. This release adds 100840 cases across 20168 failure mechanisms and 254 domains.
The open tier gives you the failure and the unsuccessful fix for one case in every mechanism. The remaining 80672 cases, 5 variants per mechanism, are member-only: the verified repair, its recorded checks, and the full fixture suite are held in the member archive. Read the methodology ↗
A RECORD OF WHAT WENT WRONG
Browse the archive / 100840
Divisor count square root pair · case 01
A square-root divisor is counted twice.
Divisor count square root pair · case 02
A square-root divisor is counted twice.
Divisor count square root pair · case 03
A square-root divisor is counted twice.
Divisor count square root pair · case 04
A square-root divisor is counted twice.
Divisor count square root pair · case 05
A square-root divisor is counted twice.
Prime predicate small boundary · case 01
The empty divisor loop falsely accepts zero and one.
Prime predicate small boundary · case 02
The empty divisor loop falsely accepts zero and one.
Prime predicate small boundary · case 03
The empty divisor loop falsely accepts zero and one.
Prime predicate small boundary · case 04
The empty divisor loop falsely accepts zero and one.
Prime predicate small boundary · case 05
The empty divisor loop falsely accepts zero and one.
Carmichael number predicate · case 01
A base-two Fermat congruence admits primes as Carmichael numbers.
Carmichael number predicate · case 02
A base-two Fermat congruence admits primes as Carmichael numbers.
Carmichael number predicate · case 03
A base-two Fermat congruence admits primes as Carmichael numbers.
Carmichael number predicate · case 04
A base-two Fermat congruence admits primes as Carmichael numbers.
Carmichael number predicate · case 05
A base-two Fermat congruence admits primes as Carmichael numbers.
Euler totient · case 01
The prime-only totient shortcut is applied to composite numbers.
Euler totient · case 02
The prime-only totient shortcut is applied to composite numbers.
Euler totient · case 03
The prime-only totient shortcut is applied to composite numbers.
Euler totient · case 04
The prime-only totient shortcut is applied to composite numbers.
Euler totient · case 05
The prime-only totient shortcut is applied to composite numbers.
Prime factor multiplicity · case 01
Distinct prime divisors discard their multiplicities.
Prime factor multiplicity · case 02
Distinct prime divisors discard their multiplicities.
Prime factor multiplicity · case 03
Distinct prime divisors discard their multiplicities.
Prime factor multiplicity · case 04
Distinct prime divisors discard their multiplicities.
Prime factor multiplicity · case 05
Distinct prime divisors discard their multiplicities.
Radical distinct prime product · case 01
Repeated prime powers are retained in the radical.
Radical distinct prime product · case 02
Repeated prime powers are retained in the radical.
Radical distinct prime product · case 03
Repeated prime powers are retained in the radical.
Radical distinct prime product · case 04
Repeated prime powers are retained in the radical.
Radical distinct prime product · case 05
Repeated prime powers are retained in the radical.
Trailing factorial zeroes · case 01
Only one factor of five per multiple is counted.
Trailing factorial zeroes · case 02
Only one factor of five per multiple is counted.
Trailing factorial zeroes · case 03
Only one factor of five per multiple is counted.
Trailing factorial zeroes · case 04
Only one factor of five per multiple is counted.
Trailing factorial zeroes · case 05
Only one factor of five per multiple is counted.
Factorial prime valuation · case 01
Prime-power multiplicities in a factorial are omitted.
Factorial prime valuation · case 02
Prime-power multiplicities in a factorial are omitted.
Factorial prime valuation · case 03
Prime-power multiplicities in a factorial are omitted.
Factorial prime valuation · case 04
Prime-power multiplicities in a factorial are omitted.
Factorial prime valuation · case 05
Prime-power multiplicities in a factorial are omitted.
Modular multiplicative inverse · case 01
Fermat inversion is used without a prime-modulus precondition.
Modular multiplicative inverse · case 02
Fermat inversion is used without a prime-modulus precondition.
Modular multiplicative inverse · case 03
Fermat inversion is used without a prime-modulus precondition.
Modular multiplicative inverse · case 04
Fermat inversion is used without a prime-modulus precondition.
Modular multiplicative inverse · case 05
Fermat inversion is used without a prime-modulus precondition.
Modular negative exponent · case 01
A negative exponent is replaced with its magnitude.
Modular negative exponent · case 02
A negative exponent is replaced with its magnitude.
Modular negative exponent · case 03
A negative exponent is replaced with its magnitude.
Modular negative exponent · case 04
A negative exponent is replaced with its magnitude.
Modular negative exponent · case 05
A negative exponent is replaced with its magnitude.
Perfect number predicate · case 01
Self-divisors are included in the perfect-number equality.
Perfect number predicate · case 02
Self-divisors are included in the perfect-number equality.
Perfect number predicate · case 03
Self-divisors are included in the perfect-number equality.
Perfect number predicate · case 04
Self-divisors are included in the perfect-number equality.
Perfect number predicate · case 05
Self-divisors are included in the perfect-number equality.
Abundant number predicate · case 01
Perfect numbers are included at the abundance boundary.
Abundant number predicate · case 02
Perfect numbers are included at the abundance boundary.
Abundant number predicate · case 03
Perfect numbers are included at the abundance boundary.
Abundant number predicate · case 04
Perfect numbers are included at the abundance boundary.
Abundant number predicate · case 05
Perfect numbers are included at the abundance boundary.
Squarefree predicate · case 01
A nonsquare can still contain a squared prime factor.
Squarefree predicate · case 02
A nonsquare can still contain a squared prime factor.
Squarefree predicate · case 03
A nonsquare can still contain a squared prime factor.
Squarefree predicate · case 04
A nonsquare can still contain a squared prime factor.
Squarefree predicate · case 05
A nonsquare can still contain a squared prime factor.
Multiplicative order · case 01
Starting at exponent zero returns the trivial identity.
Multiplicative order · case 02
Starting at exponent zero returns the trivial identity.
Multiplicative order · case 03
Starting at exponent zero returns the trivial identity.
Multiplicative order · case 04
Starting at exponent zero returns the trivial identity.
Multiplicative order · case 05
Starting at exponent zero returns the trivial identity.
Digital root base ten · case 01
A zero remainder represents nine for nonzero multiples.
Digital root base ten · case 02
A zero remainder represents nine for nonzero multiples.
Digital root base ten · case 03
A zero remainder represents nine for nonzero multiples.
Digital root base ten · case 04
A zero remainder represents nine for nonzero multiples.
Digital root base ten · case 05
A zero remainder represents nine for nonzero multiples.
Decimal digit count · case 01
The minus sign is counted as a decimal digit.
Decimal digit count · case 02
The minus sign is counted as a decimal digit.
Decimal digit count · case 03
The minus sign is counted as a decimal digit.
Decimal digit count · case 04
The minus sign is counted as a decimal digit.
Decimal digit count · case 05
The minus sign is counted as a decimal digit.
Decimal palindrome magnitude · case 01
A sign character participates in a magnitude-only comparison.
Decimal palindrome magnitude · case 02
A sign character participates in a magnitude-only comparison.
Decimal palindrome magnitude · case 03
A sign character participates in a magnitude-only comparison.
Decimal palindrome magnitude · case 04
A sign character participates in a magnitude-only comparison.
Decimal palindrome magnitude · case 05
A sign character participates in a magnitude-only comparison.
Integer cube root floor · case 01
Nearest root differs from a floor root between cubes.
Integer cube root floor · case 02
Nearest root differs from a floor root between cubes.
Integer cube root floor · case 03
Nearest root differs from a floor root between cubes.
Integer cube root floor · case 04
Nearest root differs from a floor root between cubes.
Integer cube root floor · case 05
Nearest root differs from a floor root between cubes.
Ordered samples without replacement · case 01
Unordered selection drops permutation multiplicity.
Ordered samples without replacement · case 02
Unordered selection drops permutation multiplicity.
Ordered samples without replacement · case 03
Unordered selection drops permutation multiplicity.
Ordered samples without replacement · case 04
Unordered selection drops permutation multiplicity.
Ordered samples without replacement · case 05
Unordered selection drops permutation multiplicity.
Unordered samples without replacement · case 01
Ordered arrangements overcount each selected subset.
Unordered samples without replacement · case 02
Ordered arrangements overcount each selected subset.
Unordered samples without replacement · case 03
Ordered arrangements overcount each selected subset.
Unordered samples without replacement · case 04
Ordered arrangements overcount each selected subset.
Unordered samples without replacement · case 05
Ordered arrangements overcount each selected subset.
INSPECTABLE BY DESIGN
Every result has a runnable source.
Runnable implementations with recorded outputs, source hashes, and explicit contracts. Related variants share a failure mechanism and belong together in evaluation splits.
Read the methodology ↗