introduces: if _ then _ else _ , when _ then _ , there is _ , not _ ,
        both _ , either _ , all _ , any _ . 

includes:   Instant/Distinction ( truth-value for s , _ is _ ) .

needs:	    Tuples/Basics .  truth-value <= component .

if_then_else _ 	:: truth-value, x, y -> x | y (linear) . 
when _ then _ 	:: truth-value, x -> x (partial) . 
there is _ 	:: x -> true (total) . 
not _ 		:: truth-value -> truth-value (total, injective) . 
both _ 		:: (truth-value, truth-value) -> truth-value 
                	   (total, associative, commutative, idempotent, unit is true) . 
either _ 	:: (truth-value, truth-value) -> truth-value 
			   (total, associative, commutative, idempotent, unit is false) . 
all _ 		:: truth-value* -> truth-value 
			   (total, associative, commutative, idempotent, \unit is true) . 
any _ 		:: truth-value* -> truth-value 
			   (total, associative, commutative, idempotent, unit is false) . 
_ is _ 		:: truth-value, truth-value -> truth-value (total) .
(1) (if t:truth-value then x else y) = when t then x | when not t then y .
(2) (when true then x) = x ; (when false then x) = nothing .
(3) (there is x!) = true ; (there is nothing) = nothing .
(4) (not true) = false ; (not not t:truth-value) = t .
(5) both (t:truth-value, u:truth-value) = if t then u else false ;
       	both (t:truth-value, u:truth-value) = true => t = true .
(6) either (t:truth-value, u:truth-value) = if t then true else u ;
       	either (t:truth-value, u:truth-value) = false => t = false .
(7) all (s1:truth-value, s2:truth-value) = both (s1, s2) .
(8) any (s1:truth-value, s2:truth-value) = either (s1, s2) .
(9) true is false = false .