We define a notion of concordance based on Euler characteristic, and show that it gives rise to a concordance group of links in , which has the concordance group of knots as a direct summand with infinitely generated complement. We consider variants of this using oriented and unoriented surfaces as well as smooth and locally flat embeddings.
"Concordance groups of links." Algebr. Geom. Topol. 12 (4) 2069 - 2093, 2012. https://doi.org/10.2140/agt.2012.12.2069