Logical operators

Examples:

F ; T
## [1] FALSE
## [1] TRUE
!TRUE    # not TRUE == FALSE  
## [1] FALSE
TRUE & TRUE
## [1] TRUE
FALSE & FALSE
## [1] FALSE
TRUE & FALSE   # returns TRUE if both expressions are TRUE
## [1] FALSE
TRUE | FALSE   # returns TRUE if at least one of the two expressions is TRUE
## [1] TRUE