Logic variable

Truth/Logic value

The truth values (also called the logical values) are false and true. They represent the truth values of logic and Boolean algebra. Both are the "numerical constants" of logic.

The values false and true are logical states, not numbers.
We use symbols for write the corresponding logical state:
false = F = L = log. 0 = 0
true = T = H = log. 1 = 1

F = false, L = low
T = true, H = high

The truth values can be represented by:
switch (off, on)
voltage level (low, high)
current (no, yes)

→t V {{settings.stringLog0()}} →t V {{settings.stringLog1()}}
I > 0 A

The logical states (thruth values) can be represented by the bits too:
false = 0
true = 1

Comparison of thruth states and bits

Although the truth values are states, there are some operations (like sum).

bitsthruth states
0 + 0 = 0 + =
0 + 1 = 1 + =
1 + 0 = 1 + =
1 + 1 = 10 + =

Logic variable

Logic variable is used in logic circuit. It is named A, B, C, ... Each variable can be valuated by the one of two thruth values (false, true). Logic variable (it's state) can be represented by:
switch (off, on)
voltage level (low, high)
current (no, yes)

A = A =
→t V {{settings.stringLog0()}} →t V {{settings.stringLog1()}}
I > 0 A

The logic variable (truth variable) could be "normal" (A, B, C, ...) or negative (A, B, C). In that case the values are oposit, in case of A = True = High = Log. 1 it means that A = False = Low = Log. 0 and vice versa.

AA

Logic variable

 
   A =      A = 
A = A =
→t V {{logA ? settings.stringLog1() : settings.stringLog0()}} →t V {{!logA ? settings.stringLog1() : settings.stringLog0()}}
I > 0 A I > 0 A