 logic: free |  logic: infinitary |  logic: intuitionistic |  logic: linear |  logic: modal |  logic: paraconsistent |  logic: relevance |  logic: second-order and higher-order |  logic: substructural |  logic: temporal |  logical consequence |  logical form |  logical truth |  model theory |  model theory: first-order |  paradox: Skolem’s |  proof theory: development of 