Debono, With respect, you are extending to Ms Gillard a definition of lying that is more subjective than most people would associate with the term.
She didn't say that it was her Intention not to introduce a carbon tax. She said without qualification that she wouldn't do it. To most people that was a promise or assurance given as an enticement to vote for her.
Having used that assurance to win a very tight election she then did not honour her promise.
If I promise to give you $1,000 for a car, you give me the car then I change mind and won't pay, most people would see that as a lie, despite my original intention.
Had she been unable to fulfill her promise or in the example had I been unable to pay then most people would see this as a broken promise but not a lie.
Ms Gillard is not in that position. She gave an unqualified undertaking, she is in a position to honour it but choses not to. I believe most people would consider this both a lie and a broken promise.