Derive all four propositional logic operators from nand

In summary, the conversation discusses the use of Nand as a basic operator in propositional logic and how it can be used to derive all four of the logic operators (~, V, &, →). The truth table for Nand is also mentioned. The conversation also touches on the prevalence of Nand gates in electronic components and the potential cost benefits of using Nand. The conversation ends with a mention of NOR as another possible basic operator.
  • #1
Uvohtufo
23
0
So I recently learned that you can derive all four of the propositional logic operators (~, V, &, →) from Nand alone.

As I have understood it, so long as you have negation, and one of the other operators, you can derive the rest. Like P → Q can be defined as ~P V Q.

However, I learned that if you start with the Nand (Not and) operator, you can derive all four. I'll use ' N ' to designate Nand.

The truth table for Nand being
P Q | P N Q
T T | F
F T | T
T F | T
F F | T

~P := P N P
P & Q := (P N Q) N (P N Q)
P V Q := (P N P) N (Q N Q)
P -> Q := (P N Q) N (Q N Q)

Isn't that cool?
 
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  • #2
Yes, it's cool.

I wonder if that explains why NAND gates are common electronic components. But perhaps NAND gates are common only because the circuit is simple to construct.
 
  • #3
Stephen Tashi said:
Yes, it's cool.

I wonder if that explains why NAND gates are common electronic components. But perhaps NAND gates are common only because the circuit is simple to construct.

Yeah I am not sure.

I think its interesting how when symbolic logic was being invented, implication and negation were viewed as the basic components of logic. Today it seems like programmers view and or or and negation as basic parts.

Unlike philosophers or programmers, electronics people have a cost constraint. Nand is simpler, but is it cheapest?
 
  • #4
You have also NOR.
 
  • #5


Yes, it is indeed fascinating that all four propositional logic operators can be derived from just the Nand operator. This is a testament to the versatility and power of Nand in logical operations. By using the Nand operator, we can construct complex logical statements and derive the truth values for them. This method of deriving the operators also highlights the interdependence and connections between the different logical operators. It is a valuable tool for understanding and analyzing logical statements. Thank you for sharing this knowledge.
 

1. What is propositional logic?

Propositional logic is a branch of mathematical logic that deals with the study of logical relationships between statements or propositions. It is concerned with the truth values of propositions and the rules for combining them to form more complex statements.

2. What is NAND?

NAND is a logical operator that stands for "not and". It is represented by the symbol ⊼ and has the following truth table:
A ⊼ B | Result
0 | 1
1 | 1
1 | 1
1 | 0
NAND is equivalent to "not both" or "neither...nor" and can be used to express all other logical operators.

3. How can all four propositional logic operators be derived from NAND?

All four propositional logic operators (AND, OR, NOT, and IMPLIES) can be derived from NAND by using the two following equivalences:
1. A AND B = ¬(A ⊼ B)
2. A OR B = (A ⊼ A) ⊼ (B ⊼ B)
By using these equivalences, we can express any logical statement using only NAND.

4. What is the significance of deriving all four propositional logic operators from NAND?

Deriving all four propositional logic operators from NAND allows us to simplify logic circuits and reduce the number of gates needed. NAND gates are also easier to construct and more reliable compared to other logic gates. This method of deriving logical operators is known as "functional completeness".

5. Are there any other methods for deriving propositional logic operators?

Yes, there are other methods for deriving propositional logic operators, such as using NOR gates (the logical operator for "not or"). However, using NAND or NOR gates to derive all logical operators is considered the most efficient and widely used method.

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