Tangle sums and factorization of a-polynomials

Masaharu Ishikawa, Thomas W. Mattman, Koya Shimokawa

Research output: Contribution to journalArticlepeer-review


We show that there exist infinitely many examples of pairs of knots, K1 and K2, that have no epimorphism π1(S3 \ K1) → π1(S3 \ K2) preserving peripheral structure although their A-polynomials have the factorization AK2 (L, M) ∣ AK1 (L, M). Our construction accounts for most of the known factorizations of this form for knots with 10 or fewer crossings. In particular, we conclude that while an epimorphism will lead to a factorization of A-polynomials, the converse generally fails.

Original languageEnglish
Pages (from-to)823-835
Number of pages13
JournalNew York Journal of Mathematics
Publication statusPublished - 2015 Jan 1
Externally publishedYes


  • A polynomial
  • Knot group
  • Tangle sum

ASJC Scopus subject areas

  • Mathematics(all)


Dive into the research topics of 'Tangle sums and factorization of a-polynomials'. Together they form a unique fingerprint.

Cite this