计算机方向需要的逻辑理论Thisbookfocusesontwostylesofdeductiverules:NaturaldeductionandGentzen’scalculus.Theformerisusuallyconsideredclosertothemathematicalreasoningpracticeandyieldsadeclarativestyleofproofswhereconclusionsfollowfromassumptions.Thelatterisclosertothegoal-orientedproofconstructionmec