'ternary logic
'0 1 2
'F ? T
'False Don't know True
'LB has NOT AND OR XOR, so we implement them.
'LB has no EQ, but XOR could be expressed via EQ. In 'normal' boolean at least.

global tFalse, tDontKnow, tTrue
tFalse = 0
tDontKnow = 1
tTrue = 2

print "Short and long names for ternary logic values"
for i = tFalse to tTrue
    print shortName3$(i);" ";longName3$(i)
next
print

print "Single parameter functions"
print "x";" ";"=x";"  ";"not(x)"
for i = tFalse to tTrue
    print shortName3$(i);"  ";shortName3$(i);"    ";shortName3$(not3(i))
next
print

print "Double  parameter fuctions"
print "x";" ";"y";"  ";"x AND y";"  ";"x OR y";"  ";"x EQ y";"  ";"x XOR y"
for a = tFalse to tTrue
    for b = tFalse to tTrue
        print shortName3$(a);" ";shortName3$(b);"     "; _
            shortName3$(and3(a,b));"       "; shortName3$(or3(a,b));"       "; _
            shortName3$(eq3(a,b));"        "; shortName3$(xor3(a,b))
    next
next

function and3(a,b)
    and3 = min(a,b)
end function

function or3(a,b)
    or3 = max(a,b)
end function

function eq3(a,b)
    select case
    case a=tDontKnow or b=tDontKnow
        eq3 = tDontKnow
    case a=b
        eq3 = tTrue
    case else
        eq3 = tFalse
    end select
end function

function xor3(a,b)
    xor3 = not3(eq3(a,b))
end function

function not3(b)
    not3 = 2-b
end function

'------------------------------------------------
function shortName3$(i)
   shortName3$ = word$("F ? T", i+1)
end function

function longName3$(i)
    longName3$ = word$("False,Don't know,True", i+1, ",")
end function