From: mikko.levanto@iki.fi   
      
   On 22/01/2026 14:40, Tristan Wibberley wrote:   
   > On 22/01/2026 08:30, Mikko wrote:   
   >   
   >> I don't any web site that I could trust to meet your   
   >> requirement.However, as far as I know, all authors agree about its meaning   
   >> for ordinary logic.   
   >   
   > Essentially boolean, with undefinedness when either argument is   
   > undefined and no notion that it's true when exactly one argument "has no   
   > content" and no notion that it has no content when both arguments have none?   
      
   Boole used different symbols. the symbol ∨ is from Principia Mathematica   
   by Russell and Whitehead. In any ordinary formal logic every one can   
   from A always infer A ∨ B with any B.   
      
   Some formulations of logic do not use ∨ as a primitive symbol. In these   
   formulations it can be defined in terms of primitive symbols, e.g. as   
   ¬A → B.   
      
   --   
   Mikko   
      
   --- SoupGate-Win32 v1.05   
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