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Abbreviated linear form (Beginner's Modal Logic)

mauxdivers February 02, 2018 at 06:28 1850 views 3 comments
Dear All,

I am trying to teach myself some modal logic by reading A Short Introduction to Modal Logic by Grigori Mints. (If anyone recommends another introduction, I will look into that.)

Already on p.4 I encounter a problem. I cite. “We can also state the truth-table definitions of the logical connectives in abbreviated linear form. First of all we have

value of not-a = 1 - value of a."

Okay, I can see why, since if v(a) = 1, then v(not-a)=1-1=0, whereas it is 1 if v(a)=0. This makes perfect sense. Then Mintis proceeds to defining the truth table of the disjunctive connective V in "abbreviated linear form" as well.

"The table for V has only one zero value for the case when both arguments are zero. This gives

1) v(aVb)=max(v(a),v(b))
2) v(aV0)=v(a)
3) v(aV1)=1"

It is (1) above that I don't understand. I don't know what max(v(a),v(b)) stands for. Mintis has not previously defined the "max(v(x))". 2) and 3) are obvious to me, but not 1)...

I would appreciate any help in explaining this. I googled for "abbreviated linear form" but could not find any explanation as to what the max stands for.










Comments (3)

MindForged February 02, 2018 at 06:55 #148997
1) is just saying that the truth-value of the disjunction will be the largest number of the respective values of the disjuncts, I suppose. the "max()" function I assume returns the value of the largest of its arguments (it will return either the value of "a" (v(a)) or the value of "b" (v(b)). So if in #1 a=1 and b=0, v(aVb) will return 1. Maybe I missing something, I don;t have that text.
mauxdivers February 02, 2018 at 07:03 #148999
Great! And then min(v(a),(v(b)) says that it will be the least of them, as in the conjunction's case. You're a doll (;
MindForged February 02, 2018 at 07:06 #149002
Yep, "min()" would definitely be conjunction then, since if the values of both conjuncts isn't 1, the conjunction comes out as false (as it should). So min() will just take the lowest value. No problem!