The fundamental quandle of ribbon concordances
We describe the fundamental quandle of a properly embedded surface $Σ$ (possibly with boundary) in $\mathbb{R}^{3}\times I$ and derive its presentation in terms of its motion picture. Our study is based on the topological definition of the fundamental quandle. We prove that a ribbon concordance $C$ from a classical knot $K_1$ to a classical knot $K_0$ gives rise to a quandle monomorphism $Q(K_0)\hookrightarrow Q(C)$ and a quandle epimorphism $Q(K_1)\twoheadrightarrow Q(C)$.
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