Hello, I've been working on truth tables recently and have come across the phrase 'validity', For the last day or so I've been trying to figure out how to calculate the validity of truth tables and I've come up with this below. (p.s I was unsure if this is the right forum section or not, so if not I'm sorry for that.)

if A > C & B > C, then (A or B) > C

| A | C | A > C |.... B.......|.......... B > C ........... |.. A > C & B > C ..| .....(A or B) > C

---------------------------------- -------------------------- ----------------------- ------

| T | T |.....T....| .. .T. .. |..............T...............| .............T............. .| ..............T..............

| T | F |.....F....| .. .T. .. |..............F................| ..............F..............| ..............F...........

| F | T |.....T....| .. .F. .. |..............T................| ..............T..............| ..............T...........

| F | F |.....T....| .. .F. .. |..............T................| ..............T..............| ..............T..........

I believe this to be a valid truth table, because when the premise is true, the final expression is true, and when the premise is false, so is the final expression. Can anyone confirm/deny and explain why.

many thanks to all that reply.