### Abstract

We develop a calculus for diagrams of knotted objects. We define arrow presentations, which encode the crossing information of a diagram into arrows in a way somewhat similar to Gauss diagrams, and more generally w–tree presentations, which can be seen as “higher-order Gauss diagrams”. This arrow calculus is used to develop an analogue of Habiro’s clasper theory for welded knotted objects, which contain classical link diagrams as a subset. This provides a “realization” of Polyak’s algebra of arrow diagrams at the welded level, and leads to a characterization of finitetype invariants of welded knots and long knots. As a corollary, we recover several topological results due to Habiro and Shima and to Watanabe on knotted surfaces in 4–space. We also classify welded string links up to homotopy, thus recovering a result of the first author with Audoux, Bellingeri and Wagner.

Original language | English |
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Pages (from-to) | 397-456 |

Number of pages | 60 |

Journal | Algebraic and Geometric Topology |

Volume | 19 |

Issue number | 1 |

DOIs | |

Publication status | Published - 2019 Feb 6 |

### ASJC Scopus subject areas

- Geometry and Topology

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## Cite this

*Algebraic and Geometric Topology*,

*19*(1), 397-456. https://doi.org/10.2140/agt.2019.19.397