On 2-complexes embeddable in 4-space, and the excluded minors of their underlying graphs
<|reference_start|>On 2-complexes embeddable in 4-space, and the excluded minors of their underlying graphs: We study the potentially undecidable problem of whether a given 2-dimensional CW complex can be embedded into $\mathbb{R}^4$. We provide operations that preserve embeddability, including joining and cloning of 2-cells, as well as $\Delta\mathrm Y$-transformations. We also construct a CW complex for which $\mathrm Y\Delta$-transformations do not preserve embeddability.   We use these results to study 4-flat graphs, i.e., graphs that embed in $\mathbb{R}^4$ after attaching any number of 2-cells to their cycles; a graph class that naturally generalizes planarity and linklessness. We verify several conjectures of van der Holst; in particular, we prove that each of the 78 graphs of the Heawood family is an excluded minor for the class of 4-flat graphs.<|reference_end|>
@article{georgakopoulos2024on,
    title={On 2-complexes embeddable in 4-space, and the excluded minors of their
  underlying graphs},
    author={Agelos Georgakopoulos, Martin Winter},
    journal={arXiv preprint arXiv:2408.12681},
    year={2024},
    archivePrefix={arXiv},
    eprint={2408.12681},
    primaryClass={math.CO cs.DM math.GT}
}