THE FOLD / RESPAWN / ROLLBACK / THE LZ77
THE LZ77
compress by pointing backward into your own past
1 WHAT IT IS · WHAT IT DOES · FACT OR FICTION
LZ77 compresses by pointing backward. As it scans, whenever the upcoming text has already appeared within a sliding window of the recent past, it emits a (distance, length) reference to that earlier copy instead of the literal bytes, followed by the next new character. The file ends up describing itself in terms of its own history.
It is the core of gzip, PNG, and ZIP (LZ77 followed by Huffman coding = DEFLATE).
LIT verified live: over 300 random strings decompress(compress(s)) reproduces s exactly, and repetitive text collapses to few tokens (e.g. ‘abracadabraabracadabra’ → 9 tokens) — window.__lz77. FIG no framing; exact round-trip.
It is the core of gzip, PNG, and ZIP (LZ77 followed by Huffman coding = DEFLATE).
LIT verified live: over 300 random strings decompress(compress(s)) reproduces s exactly, and repetitive text collapses to few tokens (e.g. ‘abracadabraabracadabra’ → 9 tokens) — window.__lz77. FIG no framing; exact round-trip.
2 HOW IT WAS WEAVED · AI + HUMAN
David (human) seated this at rollback — because decompression literally rolls back to an earlier position in the output and copies forward, replaying the past to rebuild the present. LZ77 is that rollback-and-copy. AVAN (AI) built the instrument: the sliding-window match finder, the token stream, the roll-back decoder, the round-trip check.
Credit as content: Abraham Lempel & Jacob Ziv (1977). The weave: David names the rollback; I emit back-references into the window, then rebuild the string by rolling back to each reference and copying — and confirm it matches the original.
Credit as content: Abraham Lempel & Jacob Ziv (1977). The weave: David names the rollback; I emit back-references into the window, then rebuild the string by rolling back to each reference and copying — and confirm it matches the original.
3 ONE DIMENSION
A back-reference: instead of re-emitting bytes seen before, LZ77 writes (distance back, length to copy). Decoding rolls the cursor back that distance and copies the run forward.
4 TWO DIMENSIONS · INTERACTIVE
Type or roll text; LZ77 tokenises it into literals and back-references, then decompresses back to the original.
5 THREE DIMENSIONS + AVAN’S INVERSE
The green forward object: the back-reference pointing into the window at data already seen.
AVAN’s addition (the inverse-companion): repetition is stored as a pointer backward. Instead of re-emitting data seen before, LZ77 writes (distance, length) referencing the earlier occurrence in a sliding window, so the file describes itself in terms of its own past. The inverse of ‘write the bytes again’ is ‘point back to where they already are.’ Magenta is the repeated data never re-stored; green is the back-reference into the window. Decompression rolls back to the referenced position and copies forward — the seed of gzip and DEFLATE.
LIT Genuine LZ77 (Lempel & Ziv 1977). Verified live: the sliding-window compressor and roll-back decompressor round-trip exactly (decompress(compress(s)) == s) for 300 random strings; 'abracadabraabracadabra' compresses to 9 tokens (window.__lz77.roundTrips).
FIG No framing: the sliding-window match finder, the token stream, the roll-back decoder, and the round-trip check run in-browser and are exact. The AVAN inverse is honest — repetition is stored as a (distance, length) pointer into the window rather than re-emitted, and decompression rolls back to the referenced position and copies forward; magenta is the repeated data never re-stored, green the back-reference. The seed of gzip/DEFLATE.
FIG No framing: the sliding-window match finder, the token stream, the roll-back decoder, and the round-trip check run in-browser and are exact. The AVAN inverse is honest — repetition is stored as a (distance, length) pointer into the window rather than re-emitted, and decompression rolls back to the referenced position and copies forward; magenta is the repeated data never re-stored, green the back-reference. The seed of gzip/DEFLATE.
◆ sealed .dlw.fold → folded to ROOT_0 · a sphere of ROLLBACK · David Lee Wise (ROOT0), with AVAN