# What determines the inputs for logic gates?

I am looking at the solutions page for the Boolean project #2 and I am trying to figure out how to determine what the inputs would be on the logic gate. On this example below on the screenshot there are 4 variables with 1,1,1,0 as the beginning inputs from top to bottom. How do I determine this? - thanks!!

I asked this same question and I could be wrong about this but I came to the following conclusion after a bunch of research. You know that the Kmap above your logic circuit is derived from a truth table. Each row of that table has a column that corresponds to a variable (in this case w, x, y, or z) in each row under any given variable is a false or positive statement (0 or 1). These are equal to inputs. The last column of the truth table is the Function column (F) and it shows the output depending on the input of each variable for example, w = 0, x = 0, y =1 and z = 0 and if we apply that to your logic circuit pictured above, your output would be 0 (assuming the the top input box is w, second down from that is x etc). In other words your logic circuit is equivalent to your simplified equation and if you plug in the variables from the truth table that the Kmap was derived from you should get the corresponding output that is the F column of the truth table. I hope that makes sense and didn’t confuse you more. In this screen shot you can switch w with A, x with B, y with C and z with D. Now if you pick any give row underneath the very top row you get corresponding inputs for w, x, y and z. Those would be the four inputs in the four boxes in the circuit you presented. That last cell in that same row is the output (F) and when you plug in true or false values for w, x, y and z, your output should come out as the same as the output as that last cell in that same row (F). This truth table is just an example. It will not apply to your specific circuit. I was just using it as a visual example. Also, this table is how you make the Kmap but it’s easier to use this table to figure out what your inputs and their corresponding outputs should be.

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Ok. yes! that makes sense. Thank you!