Knot theory 3 Low-dimensional topology 3 Manifolds and cell complexes -- Low-dimensional topology -- Knots and links in $S^3$ 2 Topology 2 Algebraic topology 1 Algebraic topology -- Classical topics -- Degree, winding number 1 Algebraic topology -- Homology and cohomology theories -- Other homology theories 1 Biology and other natural sciences -- Chemistry -- Molecular structure (graph-theoretic methods, methods of differential topology, etc.) 1 Biology and other natural sciences -- Genetics and population dynamics -- Protein sequences, DNA sequences 1 Biology and other natural sciences -- Physiological, cellular and medical topics -- Biochemistry, molecular biology 1 Combinatorial topology 1 Differential topology 1 Geometry 1 Group theory and generalizations -- Other generalizations of groups -- Loops, quasigroups 1 Group theory and generalizations -- Other generalizations of groups -- Sets with a single binary operation (groupoids) 1 Group theory and generalizations -- Permutation groups -- General theory for finite groups 1 Information and communication, circuits -- Circuits, networks -- Applications of graph theory 1 Knot theory-- Braid theory-- Alexander ideals-- Low-Dimensional topology 1 Low dimensional topology 1 Manifolds and cell complexes -- Low-dimensional topology -- Fundamental group, presentations, free differential calculus 1 Manifolds and cell complexes -- Low-dimensional topology -- Invariants of knots and 3-manifolds 1 Manifolds and cell complexes -- Low-dimensional topology -- Relations with graph theory 1 Manifolds and cell complexes -- PL-topology -- Knots and links (in high dimensions) 1 Mathematics 1 Molecular biology 1 Topological manifolds 1 Topological spaces 1