I'd really appreciate if someone could tell me how to determine the variable order in a truth table e.g. how should we go about creating a truth table for the Boolean expression (y.x)+w?

Are we supposed to list these Boolean variables in alphabetical order:

w|x|y|(y.x)|(y.x)+w

0|0|0|

0|0|1|

0|1|0|

0|1|1|

1|0|0|

1|0|1|

1|1|0|

1|1|1|

 

Or do we list them in the order they appear in the expression(left to right):

y|x|w|(y.x)|(y.x)+w

0|0|0|

0|0|1|

0|1|0|

0|1|1|

1|0|0|

1|0|1|

1|1|0|

1|1|1|

it doesn't matter, so long as all cases are covered.

w|x |y |(y.x)|(y.x)+w

0|0|0 | 0 | 0

0|0|1 | 0 | 0

0|1|0 | 0 | 0

0|1|1 | 1 | 1

1|0|0 | 0 | 1

1|0|1 | 0 | 1

1|1|0 | 0 | 1

1|1|1 | 1 | 1

 

y|x |w |(y.x)|(y.x)+w

0|0|0 | 0 | 0

0|0|1 | 0 | 1

0|1|0 | 0 | 0

0|1|1 | 0 | 1

1|0|0 | 0 | 0

1|0|1 | 0 | 1

1|1|0 | 1 | 1

1|1|1 | 1 | 1

 

 

How come it doesn't matter; the output is different, isn't it?

They're the same table, just arranged differently.

How come it doesn't matter; the output is different, isn't it?

 

It's not a different output. The table is just a way to visualize the assignment function. All you've done is rearrange the rows.