Drawing circuits with NAND gates

[shamieh]

A cheap way to implement this circuit is to use only NAND gates. Draw the circuit diagram for the lowest cost implementation using these gates. (reminder: you can wire a NAND gate such that it acts like an inverter).

$f$(w,x,y,z) = \(\displaystyle x*y + w*x + \bar{y}*\bar{z}\)

My solution:
Will this work?

 

[Evgeny.Makarov]

Will this work?

Close, but the problem statement says you can use only NAND gates, in particular, no NOT gates. However, NOT is easily expressible through NAND.

 

[shamieh]

Wow the fact that you got that your drew that diagram on here is awesome lol. But where is the y y and z z coming from? aren't those unnecesarry?

 

[Evgeny.Makarov]

But where is the y y and z z coming from? aren't those unnecesarry?

I don't understand the question, "Where are they coming from?". Do you know where x is coming from? What's the difference between x and y?

 

[shamieh]

Nevermind, I see now.