arXiv:2503.16330v2
Abstract
Continued fraction expansions provide a well-established bridge between algebraic properties of numbers and combinatorics on words. In this article, we investigate the algebraicity of -adic numbers whose continued fractions arise from certain classes of words which generalize the classical automatic, periodic and palindromic words. Our main result shows that, under mild conditions on the -adic continued fraction expansion, such numbers are either algebraic of degree at most 2 or transcendental. This result provides an analogue of results of Bugeaud and Adamczewski-Bugeaud in the real setting and extends previous works that were limited to specific choices of -adic floor functions and less general classes of words.
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Detailed mathematical audit
01Statements3 reported findingsCorrect
The algebraic-degree dichotomy for the two stated classes of -adic continued fractions and its Ruban, Browkin, and automatic-word corollaries are correct as stated.
Quadratic-or-transcendental dichotomy
Pages 3, 9–10, and 22–32 · Theorem 1.4, Theorems 4.1 and 4.3, and Section 6 · arXiv:2503.16330v2
For both combinatorial hypotheses, long repeated or reversed blocks produce simultaneous linear forms in the convergent numerators and denominators. The bounded archimedean and -adic continuant hypotheses give the height control needed for the Subspace Theorem, while the lower bounds on the partial quotients force the required -adic smallness. An infinite fixed linear relation then implies eventual periodicity, hence rationality or quadraticity; otherwise the number is transcendental. The separate word configurations in Theorems 4.1 and 4.3 cover the stated alternatives without an omitted case.
Full paper, version 2 ↗Ruban and Browkin continued fractions
Pages 3–4 and 10 · Corollary 1.5 and its specialization · arXiv:2503.16330v2
For the Ruban and Browkin floor functions, the standard size properties of the partial quotients imply the lower bounds and continuant estimates required by Theorem 1.4. Substitution therefore gives the stated rational, quadratic, or transcendental alternatives; no stronger conclusion than the hypotheses support is asserted.
Automatic two-letter partial-quotient words
Pages 4 and 31–32 · Corollary 1.6 and the final proof · arXiv:2503.16330v2
A non-eventually-periodic automatic word over two allowed partial quotients has the bounded-repetition structure used in Theorem 4.1 or the reversed-prefix structure used in Theorem 4.3. The two fixed digits make all continuant growth conditions uniform. Eventual periodicity gives the rational or quadratic cases, while the nonperiodic case satisfies the transcendence criterion.
02Proofs4 reported findingsCorrect
The continuant estimates and the two Subspace-Theorem arguments are correct and complete. One terminal coefficient list contains a harmless extra symbol, which is a uniquely identifiable typo and does not affect the proof.
Continuant identities and height estimates
Pages 6–9 · Section 3 · arXiv:2503.16330v2
The matrix product for -adic convergents gives the determinant and concatenation identities with the displayed signs. The archimedean bounds follow from the assumed bounded continuants, while the -adic estimates use the strict size of each partial quotient. These estimates control every coordinate and every local linear form used in Section 6 with constants independent of the repeated-block index.
Repeated-block Subspace-Theorem argument
Pages 22–27 · Lemma 6.1 and Section 6.1 · arXiv:2503.16330v2
The repeated prefix produces rational approximants whose relevant local products decay faster than the height allowed by the hypotheses. Schlickewei's Subspace Theorem therefore yields a fixed nonzero linear relation along an infinite subsequence. The determinant identities exclude the degenerate coefficient patterns, and the remaining relation forces the continued fraction to be eventually periodic unless the number is transcendental. The rational and quadratic alternatives are retained exactly as stated.
Palindromic and reversed-block cases
Pages 27–31 · Sections 6.2–6.4 · arXiv:2503.16330v2
The three possible placements of the reversed block lead to the three displayed vectors of convergent data. In each case the continuant symmetry supplies the extra small linear form, and the same height computation meets the Subspace-Theorem exponent. The subsequent coefficient elimination uses nonzero continuant determinants and exhausts all cases, yielding eventual periodicity or transcendence.
An unused fourth coefficient is listed accidentally
Page 25 · final paragraph of the proof using three coordinates · arXiv:2503.16330v2
The proof says that there are not all zero, but the ambient vector has three coordinates and the immediately following relation contains only . Delete . The Subspace Theorem supplies exactly the three coefficients used in the displayed equation, so this correction is unique and changes no argument.
Full paper, version 2 ↗03Novelty0 reported findingsNo non-novelty findings
No non-novelty findings.