The Holocaust Denier Conference

You have to distinguish between holocaust denial and holocaust doubters. I don't think that Irving and co have the slightest doubt that the holocaust is a historical fact. Claiming the opposite is a tactic, not a belief. Irving only started the holocaust denier schtick after the media reaction to Hitler's war where he disputed the extent of Hitler's personal involvement. His original theory that the holocaust was performed without Hitler's knowledge by subordinates trying to please is not intrinsically anti-semitic, just utterly wrong. His later move to full fledged holocaust denial was clearly motivated by anti-semitism (see earlier).

The conference in Iran is not a sincere attempt to discover the truth, it is a political event staged for the purpose of demonstrating that Ahmadinejad is just possibly nuts enough to attack Israel if provoked.

Ahmadinejad has good reason to expect that the US might try to invade. The Axis of evil speech was tantamount to a declaration of war. Iran would be much harder to defeat but Bush might make the attempt anyway

The real message of the conference was 'attack me and I will attack Israel'. Ahmadinejad has the means to do that and to close the Straits of Hormuz and most of the gulf refineries and ports. Unlike the US or Israeli forces there will be absolutely no doubt as to whether Iran is intentionally targetting civilians, there will not even be the pretence of concealment.