$2$-categories 81t4581t4081t3081t0581t6070s0518d0518d5055n34 algebraictopology axiomaticquantumfieldtheory;operatoralgebras branes) categorieswithstructure categorytheory;homologicalalgebra classicalfieldtheories conformalfieldtheories congresses doublecategories ellipticcohomology etc homologyandcohomologytheories lagrangianformalismandhamiltonianformalism mathematics mechanicsofparticlesandsystems operads quantumfieldtheory quantumfieldtheory;relatedclassicalfieldtheories quantumtheory stringmodels supersymmetricfieldtheories topologicalfields topologicalfieldtheories two-dimensionalfieldtheories