Pages on Selectivity.net

About

Sat, 24 Oct 2026 00:00:00 +0000

Selectivity is a command line reducer for failing inputs. It works on lines in a file or files in a directory, with an optional pass over the lines inside the files that remain. A command you supply decides whether the behavior of interest still occurs. Selectivity keeps a removal only when every configured observation confirms it.

The project exists because debugging a large input often starts with the same tedious exercise: remove something, rerun the program, check that the same problem survives, then repeat. Automating that exercise gives a developer a smaller input to inspect and a more useful attachment for a bug report. The developer still defines the failure. Selectivity does not diagnose the program or infer which crash matters.

Contact

Sat, 24 Oct 2026 00:00:00 +0000

Write to info@selectivity.net with questions about Selectivity, integration work or a reduction that behaves unexpectedly.

For a reproducible bug, the GitHub repository is also a useful starting point. Include the version, operating system and predicate contract, with a small input you can share. Avoid sending private production data. Reports can contain command arguments and captured program output, so check them before attaching anything.

Demo

Sat, 24 Oct 2026 00:00:00 +0000

Watch the candidate checks from a real run of the released Selectivity 0.1.1 binary. Choose the generated 20000-line input or the small directory bundle, then play the recording or advance one check at a time. The display distinguishes the candidate being tested from the latest input accepted by the predicate. A rejected candidate can be smaller than the saved input; it was rejected because its behavior did not qualify.

This is recorded evidence, rather than a command running in your browser. The line fixture needs alpha and omega. The directory fixture needs alpha in a.txt and omega in nested/b.txt. Both runs used a Linux amd64 container, one observation per candidate, and a five-second execution timeout. The command line default is three observations. The original input sizes were 408866 bytes and 39 bytes respectively.

Download

Sat, 24 Oct 2026 00:00:00 +0000

Selectivity is free software under Apache 2.0. Each archive includes the executable, manual and license notices. Choose the operating system and processor for the machine that will run your predicate.

Linux on Intel or AMD 64-bit

Linux on ARM64

macOS on Intel

macOS on Apple Silicon

Windows on Intel or AMD 64-bit

Use SHA256SUMS to check a downloaded archive. The permanent links above follow the latest full release. Versioned archives and release notes remain on the GitHub releases page.

Quick Start

Sat, 24 Oct 2026 00:00:00 +0000

Download the archive for your operating system from the download page and unpack it. Selectivity runs as one executable. On Linux or macOS, this small example starts with four lines and keeps the one recognized by grep:

printf 'first\nTRIGGER\nthird\nfourth\n' > failing.txt
./selectivity --input failing.txt --out reduction -- grep -q TRIGGER '{input}'

Open reduction/report.html when the run finishes. The original input is copied to reduction/original and the latest accepted input is saved as reduction/reduced. The output directory must be new, its parent must exist, and it must be outside the input. Command options go before the separator. The braces are part of the placeholder, so keep them.

Reference

Sat, 24 Oct 2026 00:00:00 +0000

Selectivity removes chunks from an ordered input and asks a predicate whether the behavior of interest survives. When a removal fails, it tries smaller chunks. Each accepted deletion restarts the search, ending with checks of single remaining units. Directory mode removes whole files, optionally reduces each remaining file by lines, and repeats until a full pass leaves the modeled input unchanged.

The predicate uses exit 0 for interesting input, 1 for uninteresting input and other exits for unresolved input. Every configured observation must return 0 before a candidate is accepted. Mixed observations are unstable, timeouts are unresolved, and neither justifies deletion. An original input that does not consistently satisfy the predicate is rejected before reduction. A final repeated check confirms the saved result at the end of a completed run.