Fitness Arena

The Fitness Arena is where mutants fight for survival. Every mutant spawned by HezGene must pass through a 5-Ring Gauntlet before it can be considered as a replacement for the original function.

The 5-Ring Gauntlet

Ring 1: Correctness

The most critical ring. The mutant must produce 100% identical outputs to the original for all test inputs. If a mutant changes behavior in any way — even by a single decimal place — it is immediately killed.

Ring 2: Speed

The mutant is benchmarked against the original across hundreds of executions using high-precision timers. Speed is measured in milliseconds with statistical averaging to eliminate noise.

Ring 3: Memory

Using Python's tracemalloc, the arena measures exact byte allocations for both the original and the mutant. Lower memory usage is rewarded.

Ring 4: Edge Cases

The arena fuzz-tests the mutant with extreme and unexpected inputs: None, empty lists, massive integers, negative numbers, special characters. The mutant must handle all of them gracefully.

Ring 5: Readability

Readability is scored using cyclomatic complexity and line count. A mutant that is faster but more complex gets a lower readability score. The final fitness is a weighted combination of all five rings.

Fitness scoring

Tournament selection

After all mutants are scored, the tournament manager compares the best mutant against the original. The mutant must exceed a minimum improvement threshold (default: 0.1%) to be selected as the winner. This prevents trivially small optimizations from triggering unnecessary file changes.