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
Clear lowest set bit · case 01
Subtracting one also sets trailing zero bits.
Clear lowest set bit · case 02
Subtracting one also sets trailing zero bits.
Clear lowest set bit · case 03
Subtracting one also sets trailing zero bits.
Clear lowest set bit · case 04
Subtracting one also sets trailing zero bits.
Clear lowest set bit · case 05
Subtracting one also sets trailing zero bits.
Isolate lowest set bit · case 01
Clearing the low bit is confused with extracting it.
Isolate lowest set bit · case 02
Clearing the low bit is confused with extracting it.
Isolate lowest set bit · case 03
Clearing the low bit is confused with extracting it.
Isolate lowest set bit · case 04
Clearing the low bit is confused with extracting it.
Isolate lowest set bit · case 05
Clearing the low bit is confused with extracting it.
Next power of two inclusive · case 01
Bit length advances exact powers unnecessarily.
Next power of two inclusive · case 02
Bit length advances exact powers unnecessarily.
Next power of two inclusive · case 03
Bit length advances exact powers unnecessarily.
Next power of two inclusive · case 04
Bit length advances exact powers unnecessarily.
Next power of two inclusive · case 05
Bit length advances exact powers unnecessarily.
Population count width mask · case 01
Counting the Python magnitude ignores finite-word two-complement representation.
Population count width mask · case 02
Counting the Python magnitude ignores finite-word two-complement representation.
Population count width mask · case 03
Counting the Python magnitude ignores finite-word two-complement representation.
Population count width mask · case 04
Counting the Python magnitude ignores finite-word two-complement representation.
Population count width mask · case 05
Counting the Python magnitude ignores finite-word two-complement representation.
Binary gray encode · case 01
OR retains overlaps that Gray coding must cancel.
Binary gray encode · case 02
OR retains overlaps that Gray coding must cancel.
Binary gray encode · case 03
OR retains overlaps that Gray coding must cancel.
Binary gray encode · case 04
OR retains overlaps that Gray coding must cancel.
Binary gray encode · case 05
OR retains overlaps that Gray coding must cancel.
Binary gray decode · case 01
Encoding a Gray word again does not decode it.
Binary gray decode · case 02
Encoding a Gray word again does not decode it.
Binary gray decode · case 03
Encoding a Gray word again does not decode it.
Binary gray decode · case 04
Encoding a Gray word again does not decode it.
Binary gray decode · case 05
Encoding a Gray word again does not decode it.
Midpoint floor no float · case 01
The floating midpoint loses integer precision and negative floor semantics.
Midpoint floor no float · case 02
The floating midpoint loses integer precision and negative floor semantics.
Midpoint floor no float · case 03
The floating midpoint loses integer precision and negative floor semantics.
Midpoint floor no float · case 04
The floating midpoint loses integer precision and negative floor semantics.
Midpoint floor no float · case 05
The floating midpoint loses integer precision and negative floor semantics.
Integer signum · case 01
Zero is assigned a positive direction.
Integer signum · case 02
Zero is assigned a positive direction.
Integer signum · case 03
Zero is assigned a positive direction.
Integer signum · case 04
Zero is assigned a positive direction.
Integer signum · case 05
Zero is assigned a positive direction.
Ceil log two capacity · case 01
Exact powers of two consume an extra address bit.
Ceil log two capacity · case 02
Exact powers of two consume an extra address bit.
Ceil log two capacity · case 03
Exact powers of two consume an extra address bit.
Ceil log two capacity · case 04
Exact powers of two consume an extra address bit.
Ceil log two capacity · case 05
Exact powers of two consume an extra address bit.
Triangular number · case 01
The final term is omitted from the arithmetic-series identity.
Triangular number · case 02
The final term is omitted from the arithmetic-series identity.
Triangular number · case 03
The final term is omitted from the arithmetic-series identity.
Triangular number · case 04
The final term is omitted from the arithmetic-series identity.
Triangular number · case 05
The final term is omitted from the arithmetic-series identity.
Sum first squares · case 01
The sum of terms is used instead of the sum of their squares.
Sum first squares · case 02
The sum of terms is used instead of the sum of their squares.
Sum first squares · case 03
The sum of terms is used instead of the sum of their squares.
Sum first squares · case 04
The sum of terms is used instead of the sum of their squares.
Sum first squares · case 05
The sum of terms is used instead of the sum of their squares.
Sum first cubes · case 01
The square-sum identity is reused for cubes.
Sum first cubes · case 02
The square-sum identity is reused for cubes.
Sum first cubes · case 03
The square-sum identity is reused for cubes.
Sum first cubes · case 04
The square-sum identity is reused for cubes.
Sum first cubes · case 05
The square-sum identity is reused for cubes.
Arithmetic progression sum · case 01
The last term is multiplied by the count instead of using the endpoint average.
Arithmetic progression sum · case 02
The last term is multiplied by the count instead of using the endpoint average.
Arithmetic progression sum · case 03
The last term is multiplied by the count instead of using the endpoint average.
Arithmetic progression sum · case 04
The last term is multiplied by the count instead of using the endpoint average.
Arithmetic progression sum · case 05
The last term is multiplied by the count instead of using the endpoint average.
Geometric integer series · case 01
The next term is confused with the series sum.
Geometric integer series · case 02
The next term is confused with the series sum.
Geometric integer series · case 03
The next term is confused with the series sum.
Geometric integer series · case 04
The next term is confused with the series sum.
Geometric integer series · case 05
The next term is confused with the series sum.
Inclusive multiples count · case 01
Interval length loses alignment to the divisor.
Inclusive multiples count · case 02
Interval length loses alignment to the divisor.
Inclusive multiples count · case 03
Interval length loses alignment to the divisor.
Inclusive multiples count · case 04
Interval length loses alignment to the divisor.
Inclusive multiples count · case 05
Interval length loses alignment to the divisor.
Sum integer range inclusive · case 01
The terminal value is excluded by a half-open iteration.
Sum integer range inclusive · case 02
The terminal value is excluded by a half-open iteration.
Sum integer range inclusive · case 03
The terminal value is excluded by a half-open iteration.
Sum integer range inclusive · case 04
The terminal value is excluded by a half-open iteration.
Sum integer range inclusive · case 05
The terminal value is excluded by a half-open iteration.
Gcd zero identity · case 01
The smaller operand is not generally a common divisor.
Gcd zero identity · case 02
The smaller operand is not generally a common divisor.
Gcd zero identity · case 03
The smaller operand is not generally a common divisor.
Gcd zero identity · case 04
The smaller operand is not generally a common divisor.
Gcd zero identity · case 05
The smaller operand is not generally a common divisor.
Least common multiple sign · case 01
Multiplication retains shared factors twice.
Least common multiple sign · case 02
Multiplication retains shared factors twice.
Least common multiple sign · case 03
Multiplication retains shared factors twice.
Least common multiple sign · case 04
Multiplication retains shared factors twice.
Least common multiple sign · case 05
Multiplication retains shared factors twice.
Coprime predicate · case 01
Nondivisibility does not imply absence of a shared factor.
Coprime predicate · case 02
Nondivisibility does not imply absence of a shared factor.
Coprime predicate · case 03
Nondivisibility does not imply absence of a shared factor.
Coprime predicate · case 04
Nondivisibility does not imply absence of a shared factor.
Coprime predicate · case 05
Nondivisibility does not imply absence of a shared factor.
Proper divisor sum · case 01
The number itself is included among proper divisors.
Proper divisor sum · case 02
The number itself is included among proper divisors.
Proper divisor sum · case 03
The number itself is included among proper divisors.
Proper divisor sum · case 04
The number itself is included among proper divisors.
Proper divisor sum · case 05
The number itself is included among proper divisors.
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 ↗