In section 47.1, first paragraph, there is the sentence: "In Chapter 45 we've even proved that ever sentence of TFL is equivalent...". I believe the word "every" meant to be added here.
In the same section, 3rd paragraph, there is the sentence "But since 'A' are equivalent, they always have the same truth value in a given valuation...". I believe that it was meant to show that "'A' and 'A' are equivalent".
In Chapter 48, in the section about the rule-soundness of "vE", it is assumed in the paragraph right under that "^E" is used rather than "vE" on line n.
Great book! I loved it as a more formal introduction! I had read some Bertrand Russell books beforehand but this definitely helped grasp some key concepts more strongly. Modal logic is fascinating and the exercise about finding a counter-interpretation in system K to "|= ~□(A ^ ~A)" definitely reshaped my understanding of logic forever.
In section 47.1, first paragraph, there is the sentence: "In Chapter 45 we've even proved that ever sentence of TFL is equivalent...". I believe the word "every" meant to be added here.
In the same section, 3rd paragraph, there is the sentence "But since '
A' are equivalent, they always have the same truth value in a given valuation...". I believe that it was meant to show that "'A' and 'A' are equivalent".In Chapter 48, in the section about the rule-soundness of "vE", it is assumed in the paragraph right under that "^E" is used rather than "vE" on line n.
Great book! I loved it as a more formal introduction! I had read some Bertrand Russell books beforehand but this definitely helped grasp some key concepts more strongly. Modal logic is fascinating and the exercise about finding a counter-interpretation in system K to "|= ~□(A ^ ~A)" definitely reshaped my understanding of logic forever.