I don't understand mathematical modeling.

My method is, five houses, five conditions (nationality, skin color, smoking, drinks, pets)

Select 25 boxes (5*5), which are nationality, color, smoking, drinks and pets from top to bottom, and number them from left to right (1-5).

Then calculate each condition repeatedly, first fill in the clear conditions in the corresponding columns, and then calculate the second time after the first time, and cross out the useless conditions (for example, after the first 1 time, Article 9 can be deleted).

It seems to be the fourth time. It is estimated that rooms 4 and 5 may be Swedish, rooms 2 and 5 may be Danish, drinking tea (it is estimated for the third time that room 2 is blue, keeping horses), and rooms 3, 4 and 5 may smoke Bauer cigarettes and keep birds. However, the Norwegian 1 smokes D cigarettes, and the house 2 keeps horses. According to article 10, people who smoke mixed cigarettes live next to cats, that is to say, cats also live in one of No.3, No.4 and No.5. To sum up, cats, dogs and birds are all in No.3, No.4, No.5, and No.2 belongs to horses, so fish farming must be 1.

1 is Norwegian.

You don't need to calculate them all.