519 algebras categories(mathematics) conformalmapping curves dualitytheory(mathematics) economics engineeringmathematics equations heatequation linear linearalgebras lineardifferentialequations linearprogramming lineartopologicalspaces mathematical mathematicaloptimization mathematics matrices operatortheory partialdifferentialoperators partiallyorderedsets partiallyorderedspaces representationsofgroups scalarfieldtheory settheory surfaces topology vectoranalysis vectorfields waveequation