(Boolean Algebra) Did I write this logic expression correctly?

In summary, the student attempted to solve the homework statement using boolean algebra, but made a mistake.
  • #1
michalodzien
4
0

Homework Statement


5c7c19e54a06b3c38414cbf3ad4e2750.png


My solution, is this correct?
This is what I came up with.
Y=A+((A*B)+B+C'+(B+C'*D)+D)
Is it safe to say that it is correct or did I make a mistake?
 

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  • #2
I’d write the intermediate expressions at the gate output and put parentheses around them until you get to the final gate.

Also I’d use the bar over an expression to indicate negation.

Lastly. You can then apply Boolean algebra to reduce the long expression to get your final expression.

Try that and see if you can validate your own work. Doing it with intermediate results helps until you get good at it.
 
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  • #3
jedishrfu said:
I’d write the intermediate expressions at the gate output and put parentheses around them until you get to the final gate.

Also I’d use the bar over an expression to indicate negation.

Lastly. You can then apply Boolean algebra to reduce the long expression to get your final expression.

Try that and see if you can validate your own work. Doing it with intermediate results helps until you get good at it.
487d6b7c22a98ebf0bf126817d93626b.png


I actually did these parts beforehand but i am not sure if what i came up with is correct and i would like to validate it before i start simplifying it.
Also i have no way to check if it correct because this is for an assignment which i will not get back with feedback but only with a grade.

If you would be so kind to help me on my mistakes and guide me to do this correctly, or just give me the answer i would appreciate it a lot. Either one is fine with me.
 

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  • #4
Your paper is very messy and hard to read.

R = A + B
X = B + C'
Y = ( ( B + C' ) * D )'

Look at the Y gate again.
 
  • #5
jedishrfu said:
Your paper is very messy and hard to read.

R = A + B
X = B + C'
Y = ( ( B + C' ) * D )'

Look at the Y gate again.
I am sorry for the paper quality.

I see i did a very silly mistake and forgot to add parentheses around B + C' and ofcourse It's a NAND gate so the expression needs a negation as a whole. I can see i did same mistake with E gate it should have been ((B+C'*D)'+D)'

This is the result i got now:

F=A+(A*B)+(B*C')+(((B+C')*D)'+D)'

It looks correct to me, does it so to you?
 
  • #6
Students are always looking for the geodesic when the real geodesic is the step by step approach with intermediate values allowing someone to review it and check each step.

R = A * B (I made a mistake as it was an AND gate)
X = B + C'
Y = ( ( B + C' ) * D )'

E = ( Y + D )' = ( ( ( B + C' ) * D )' + D )'

G = R + X + E = (A * B) + (B + C') + ( ( ( B + C' ) * D )' + D )'

F = A + G = A + (A * B) + (B + C') + ( ( ( B + C' ) * D )' + D )'

Can you check my work?
 
  • #7
jedishrfu said:
Students are always looking for the geodesic when the real geodesic is the step by step approach with intermediate values allowing someone to review it and check each step.

R = A * B (I made a mistake as it was an AND gate)
X = B + C'
Y = ( ( B + C' ) * D )'

E = ( Y + D )' = ( ( ( B + C' ) * D )' + D )'

G = R + X + E = (A * B) + (B + C') + ( ( ( B + C' ) * D )' + D )'

F = A + G = A + (A * B) + (B + C') + ( ( ( B + C' ) * D )' + D )'

Can you check my work?
It all looks correct and i can see this is an easy way to do it, thank you very much for your help!
 
  • #8
Hmmm, I don't check this forum often so I'm a bit late to the party, but I get$$C'+A+B$$when it's all said and done.
 
Last edited:

1. How do I know if I have written a logic expression correctly?

To check if a logic expression is written correctly, you can follow these steps:1. Check if the expression follows the basic rules of Boolean algebra, such as using only AND, OR, and NOT operations.2. Verify if the expression has the correct number of parentheses, with each open parenthesis having a corresponding closing parenthesis.3. Evaluate the expression using truth tables or by simplifying it using laws of Boolean algebra.4. Compare the result with the expected outcome to determine if the expression is written correctly.

2. What are the common mistakes to avoid while writing a logic expression?

Some common mistakes to avoid while writing a logic expression are:1. Using incorrect symbols, such as using “+” instead of “OR” or “-” instead of “NOT”.2. Missing or misplaced parentheses, which can change the meaning of the expression.3. Not using the correct order of operations, such as not evaluating the NOT operation first.4. Not simplifying the expression using Boolean laws, leading to a more complex and incorrect expression.

3. How can I simplify a logic expression?

To simplify a logic expression, you can use the laws of Boolean algebra. Some common laws include:1. De Morgan’s Law: ~(A&B) = ~A | ~B and ~(A|B) = ~A & ~B2. Associative Law: (A&B)&C = A&(B&C) and (A|B)|C = A|(B|C)3. Distributive Law: A&(B|C) = (A&B)|(A&C) and A|(B&C) = (A|B)&(A|C)By applying these laws, you can reduce the complexity of an expression and make it easier to evaluate.

4. What is the purpose of using Boolean algebra in logic expressions?

Boolean algebra is a mathematical system that deals with logic and binary values. It allows us to represent logical statements and operations using symbols and rules. By using Boolean algebra, we can simplify complex logical expressions, determine their truth values, and analyze their behavior. It is widely used in computer science and electronics to design and analyze digital circuits and programming logic.

5. Are there any tools or software available to help with writing logic expressions?

Yes, there are many tools and software available to assist with writing logic expressions. Some popular options include:1. Logic gate simulators, which allow you to create and evaluate digital circuits using logic gates.2. Online truth table generators, which can help you quickly generate truth tables for complex expressions.3. Boolean algebra calculators, which can simplify expressions and provide step-by-step solutions.4. Programming languages, such as Python and Java, which have built-in functions for Boolean operations and logic expressions.

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