I PM'd you a question. I suppose I could ask it here too.
You said "but to conquer a world, the amount you send must be higher than the number currently there"
In the example: "blue attacks B6 and C7 with 6 and 4 respectively."
Both B6 and C7 had 4 ships defending but you show that C7 was successful.
So is it > or >= to win a planet?