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2008/04/30 19:05:57瀏覽319|回應0|推薦0 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
A-1
B-3 將論域設限在"人",符號設定:"Lxy":"x loves y" Everyone loves someone.符號化為: (x)(∃y)Lxy Someone loves someone.符號化為: (∃x)(∃y)Lxy 證明句二的否定與句一一同是否會導出矛盾;
導出矛盾,可知若第一句為真,則第二句絕不會為假。句一為真則句二必真,因此句一蘊含句二。
C-8 符號設定:"Infinity":"a"; "Lxy":"x is larger than y"; "Cx":"x is a countable"; "Nx":"x is a number" Infinity is larger than any countable number. 符號化為: (x)(Cx&Nx⊃Lax) No number is larger than itself. 符號化為: (x)(Nx⊃–Lxx) So infinity is not a countable number.符號化為: ∴ –(Ca&Na)
得證,此為有效論證 D-3.(z)–(x)–Kzx; (∃z)(x)–Kzx
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( 知識學習|隨堂筆記 ) |