Kmaps

Note: The online tool at https://madformath.com/calculators/digital-systems/karnaugh-maps/karnaugh-map-solver, which we use in our examples, calls the Boolean variables $A$, $B$, $C$, $D$, etc., while we call our Boolean variables $x$, $y$, $z$, etc.

This naming doesn't affect the validity of the Kmap: you can name your Boolean variables whatever you wish. However, if a homework or exam question gives you a truth table that uses variables $x$, $y$, $z$, etc., you should write an answer that uses these exact variables and not $A$, $B$, $C$, $D$, etc.

That is, if a question asks you to use the above online tool, you will need to re-name your variables from $x$, $y$, $z$ into $A$, $B$, $C$ in order to use the Kmap, and then rename the variable in the final result from $A$, $B$, $C$ back to $x$, $y$, $z$.