Chvátal–Sankoff constant for a binary alphabet

Upper bound, last-listed row

| $0.826280$ | [L2009] | Computer assisted |tracked since 2026-07-24 — no movement seen yet

Lower bound, last-listed row

| $0.79970$ | [AA2026] | AI and computer assisted (unverified) |tracked since 2026-07-24 — no movement seen yet

Checked or tried against material for its cited source

• Another row, not one shown above: bound row $> 0$ line 21 citing [CS1975] — the cited source could not be read at all (tried 2026-09-11). the source we could not read (NOT read — the host did not accept a connection). Selected: drawn by its position in the list of cited rows, not because it looked wrong.
• Another row, not one shown above: bound row $0.788071$ line 23 citing [L2009] — the claim we checked: that the cited reference gives the lower bound 0.788071, obtained by a computer-assisted method, as the row's comment says. Unresolved on edition grounds only: the journal's typeset pages were not reached. The author's extended version supports every part of the claim, giving 0.788071 as the last row of its table of lower bounds, computed with a vector of 178,973,355 components, and the journal abstract names 0.788071 and 0.826280 as the improved lower and upper bounds. This verdict does not cover the body of the journal edition the entry cites, and whether the computation is correct. source link (the cited Journal of the ACM article was not reached: ACM answered 403 with a bot challenge. Read instead: the author's own extended version, a different edition, from an Internet Archive capture of his university page dated 2009-02-05 (pp. 1–20 as page images; the end of p. 22, all of p. 23 and the start of p. 24 from the text layer; p. 21, the rest of pp. 22 and 24, and pp. 25–41 not read), and the abstract of the cited article as the publisher deposited it at Crossref). Selected: drawn by its position in the list of cited rows, not because it looked wrong.

1 bound row(s) here have been checked against material for their cited source (1 drawn by position, 0 chosen because something already looked wrong). Across this whole ledger 70 row(s) have been drawn by position, against 691 rows that name a source, counted on 2026-09-27: 64 were checked against material for their cited sources and for 6 the cited source could not be read at all. 5 more were chosen for suspicion and checked; they are counted apart, because a set selected for suspicion carries no rate. Also attempted, and the source could NOT be read: the bound row $> 0$ citing [CS1975] line 21. That row is not counted as read. A row not listed here has NOT been checked.