[Verse 1]
Four parts make a grammar whole
V for variables, they control
Sigma holds the terminals tight
R makes rules that feel just right
S starts the show, the initial state
From these four, languages we create
[Chorus]
Variables to terminals flow
Production rules make structures grow
A becomes W, watch it transform
Parse trees branching, taking form
CFG, the language machine
Most elegant syntax you've ever seen
[Verse 2]
A points to W in every rule
Variables on the left, that's the tool
W can mix both types inside
Terminals and variables collide
Derivation steps, we choose our path
Leftmost, rightmost, do the math
[Chorus]
Variables to terminals flow
Production rules make structures grow
A becomes W, watch it transform
Parse trees branching, taking form
CFG, the language machine
Most elegant syntax you've ever seen
[Bridge]
But beware the ambiguous trap
Two parse trees for the same exact map
Same string, different structures made
Grammar's clarity starts to fade
Some languages inherently blur
No grammar can make them pure
[Verse 3]
From root to leaves the parse tree grows
Each node splits where production shows
Terminal symbols mark the end
Variables branch and rules extend
Every derivation tells a tale
Of how our grammar cannot fail
[Chorus]
Variables to terminals flow
Production rules make structures grow
A becomes W, watch it transform
Parse trees branching, taking form
CFG, the language machine
Most elegant syntax you've ever seen
[Outro]
Four-tuple foundation, rules that bend
Context-free grammars comprehend
Languages that compilers need
From this formal beauty, parsers feed