correction

const (
	// MaximumChangeRatio is how much of a text, as written, a correction may
	// alter. A coarse backstop against a wholesale rewrite, and against a
	// correction landing against the wrong index — a swap that would put one
	// paragraph's words where another's belong.
	MaximumChangeRatio = 0.25

	// MaximumLetterChangeRatio is the one that does the work: how much of a
	// text's letters — what is left once spacing and punctuation are set aside
	// — a correction may alter.
	//
	// Almost every real error in written Swedish is a compound split in the
	// wrong place: "Riks banken", "procent enhet", "finans departementet".
	// Repairing one moves no letters at all, only the spaces between them, so a
	// guard that looks at letters alone lets every such fix straight through
	// while a substituted word stands out immediately.
	//
	// The distinction is not academic. Asked to correct "Molntjänster och bo
	// städer", a model returned "Miljarder till bostäder" — it did not join the
	// split compound, it replaced the words with likelier ones and left the
	// meaning somewhere else entirely. Measured over the text as written that
	// came to 21%, comfortably inside the ratio above; measured over the letters
	// it is a quarter of them, and nothing like a spelling fix.
	MaximumLetterChangeRatio = 0.10

	// MinimumLetterChange is a floor under the ratio, so that a short text can
	// still have a misspelling corrected rather than being immune to correction
	// for being short.
	MinimumLetterChange = 3
)