◀ THE FOLD0ROOT.AI // WORLD II · SPAWN · FIRST LIGHT◆ .dlw.fold
THE FOLD / SPAWN / FIRST LIGHT / THE FIBONACCI WORD

THE FIBONACCI WORD

an infinite word that is its own seed
1 WHAT IT IS · WHAT IT DOES · FACT OR FICTION
The Fibonacci word is an infinite string that grows from a single letter by a rule that folds it into itself. Apply the morphism a → ab, b → a forever, starting from “a”: a, ab, aba, abaab, abaababa, …. Two miracles: each stage is the previous two concatenated (Sₙ = Sₙ₋₁ Sₙ₋₂), so its length is a Fibonacci number; and the letters themselves are golden — the fraction of a’s tends to 1/φ. It is the simplest Sturmian word: it never contains “bb” and never contains “aaa”, the most balanced non-periodic string there is.

LIT verified live: for stages 1..22, |Sₙ| is Fibonacci, Sₙ = Sₙ₋₁Sₙ₋₂, the morphism reproduces the next stage, there is no “bb” or “aaa”, and the a-fraction is 0.61803 ≈ 1/φ (window.__fibonacci_word). FIG no framing; the word is grown two ways (concatenation and morphism) and they agree.
2 HOW IT WAS WEAVED · AI + HUMAN
David (human) seated this at first-light — the whole infinite word unfolds from a single “a”, the first light of a self-similar dawn. AVAN (AI) built the instrument: generate the word by the concatenation recurrence and, independently, by applying the morphism letter-by-letter, then check the Fibonacci lengths, the golden letter-ratio, and the forbidden factors.

Credit as content: the Fibonacci word / Sturmian words (studied via Bernoulli, Christoffel, Morse–Hedlund). The weave: David names the first light; I confirm the word is its own seed — two constructions, Fibonacci lengths, and a golden density.
3 ONE DIMENSION
A stage of the word as tiles (a bright, b dark), split to show it is the previous two stages joined end to end.
4 TWO DIMENSIONS · INTERACTIVE
Step through the stages; watch the length track Fibonacci and the a-fraction settle on 1/φ, with no “bb” and no “aaa”.
5 THREE DIMENSIONS + AVAN’S INVERSE
The green forward object: the word grown by joining the two prior stages.
AVAN’s addition (the inverse-companion): don’t concatenate stages — expand every letter at once. The inverse of ‘Sₙ = Sₙ₋₁Sₙ₋₂’ is ‘replace each a by ab and each b by a, and the same word appears.’ Magenta letters are about to expand; green is the stage they become. The word is its own seed.
LIT Genuine Fibonacci word / Sturmian word (Morse–Hedlund lineage): fixed point of a→ab, b→a; Sₙ=Sₙ₋₁Sₙ₋₂; |Sₙ|=Fibonacci; a-density→1/φ; no 'bb', no 'aaa'. Verified live over stages 1..22 (window.__fibonacci_word.{lengthsFib,concatRule,morphism,noBB,noAAA,ratioPhi}).

FIG No framing: the word is grown two independent ways (concatenation recurrence and letter-by-letter morphism) and shown to agree, with Fibonacci lengths and golden density. The AVAN inverse is honest — expanding every letter at once (a→ab, b→a) reproduces the same word the concatenation builds, which is exactly why it is a morphic fixed point; magenta letters are mid-expansion, green the stage they become. The word is its own seed.
◆ sealed .dlw.fold → folded to ROOT_0 · a sphere of FIRST LIGHT · David Lee Wise (ROOT0), with AVAN