# Transform the circuit of combinational logic into a boolean expression

We have the following:

I want to transform this circuit of combinational logic into a boolean expression.

The circles mean the negation and the symbol that is used is the symbol for AND, or not?

To find that expression do we start from right to left?

• I suggest starting at the output. Anyway, is that last gate supposed to be a different type than the previous ones? Never seen it before. Also there is an electrical engineering stack exchange now. – DanielV May 2 at 17:06
• @Mary Star The final gate seems not to be an AND. Otherwise, the function would be $(\overline{x}yz)(\overline{x}\,\overline{y}z)$ which is clearly $0.$ – user376343 May 2 at 17:56

You can start from left. If there is single input NAND gate then you should assume the other input is absent that is 0. So the top most gate in left is NOT(0 AND $$x$$)=1 Similarly for bottom most gate it is also 1.
The final expression should be $$f_{x,y,x}=yz$$