Understanding bridge

The deal given in yesterday's paper is interesting. The distribution of the cards definitely suggested high bidding. North doubled the Two Spades bid because of his strength in other suits and lack of any Spades. I do not understand the logic of the Five Spades bid by South especially when East bid Four Spades against a Double by North of the Two Spades bid. This clearly indicates his strength in Spades.

Then followed Seven Diamonds and Seven Spades. South rightly passed. I cannot understand how North could assume South had the Ace of Spades. Had he got the Ace of Spades he would have definitely doubled the Seven Spades bid by East. After all, he would have had a sure trick in Ace of Spades and the bid would be down by a minimum of one trick. North's bid of Seven NT looks illogical to me, especially when South has not doubled Seven Spades and just passed. His pass clearly indicated that he has not got the Ace of Spades. North has no Spades and he can safely infer that South does not have the control in Spades.

These are purely my comments as a novice in Bridge. I would like to have an expert's views on what the basis for North's bid Seven NT is. I just want to know whether my understanding of the deal and the bidding is correct.

C RAMAKRISHNA

Jakarta