text: **Truth tables**
  
  Truth tables can be used to show how logical connectives work or how the truth values of complex 
  propositions depends on their parts. They have a column for each input variable. Each row corresponds to 
  one possible combination of the truth values these variables can take; for truth tables presented in the 
  English literature, the symbols "T" and "F" or "1" and "0" are commonly used as abbreviations for the 
  truth values "true" and "false".[56] The first columns present all the possible truth-value combinations for 
  the input variables. Entries in the other columns present the truth values of the corresponding expressions 
  as determined by the input values. For example, the expression " 
  (and). It could be used to express a sentence like "yesterday was Sunday and the weather was good". It is 
   ("the weather was good"), are 
  only true if both of its input variables, 
   (not), 
  true. In all other cases, the expression as a whole is false. Other important logical connectives are 
  , one can form 
  ). Truth tables 
  
  " uses the logical connective 
  
   (if...then), and 
  truth tables of its converse 
  can also be defined for more complex expressions that use several propositional connectives.[58] 
  
  , its inverse (  ), and its contrapositive ( 