Frylock, I didn’t read rules 11 or 12 as you did when I originally solved the problem years ago.

The way I solve these problems is by “brute force” - writing down all the possibilities at each step, indicating “branches” from previous possible solutions with a numbering system. If anyone is interested in the way I do this, it’s included below in the spoiler:

[spoiler] 1. There are five houses.

2. The Englishman lives in the red house.

3. The Spaniard owns the dog.

4. Coffee is drunk in the green house.

5. The Ukrainian drinks tea.

6. The green house is immediately to the right of the ivory house.

7. The Old Gold smoker owns snails.

8. Kools are smoked in the yellow house.

9. Milk is drunk in the middle house.

10. The Norwegian lives in the first house.

11. The man who smokes Chesterfields lives in the house next to the man with the fox.

12. Kools are smoked in the house next to the house where the horse is kept.

13. The Lucky Strike smoker drinks orange juice.

14. The Japanese smokes Parliaments.

15. The Norwegian lives next to the blue house.

Who drinks water? Who owns the zebra?

In solutions below, attributes are listed in this order: house number & nationality & colour & smoke & drink & pet

STEP 1

(rules relating to absolute house positions) 1, 9, 10, 15

Rule 1 There are five houses.

and Rule 9 Milk is drunk in the middle house.

and Rule 10 The Norwegian lives in the first house.

and Rule 15 The Norwegian lives next to the blue house.

solution A

1 Norwegian

2 blue

3 milk

4

5

STEP 2 (rules relating to relative house positions) 1, 4, 6, 9, 10, 15

Rule 4 Coffee is drunk in the green house.

and 6 The green house is immediately to the right of the ivory house.

solution A.1

1 Norwegian

2 blue

3 ivory & milk

4 green & coffee

5

solution A.2

1 Norwegian

2 blue

3 milk

4 ivory

5 green & coffee

(from now on try to use rules that are most related to information I already have)

STEP 3 (use color information since I know a lot about colors) 1, 2, 4, 6, 9, 10, 15

Rule 2 The Englishman lives in the red house.

solution A.1

1 Norwegian

2 blue

3 ivory & milk

4 green & coffee

5 Englishman & red

solution A.2

1 Norwegian

2 blue

3 Englishman & red & milk

4 ivory

5 green & coffee

STEP 4 (use color information since I know a lot about colors) 1, 2, 4, 6, 8, 9, 10, 15

Rule 8 Kools are smoked in the yellow house.

solution A.1

1 Norwegian & yellow & Kools

2 blue

3 ivory & milk

4 green & coffee

5 Englishman & red

solution A.2

1 Norwegian & yellow & Kools

2 blue

3 Englishman & red & milk

4 ivory

5 green & coffee

STEP 5 (look for nationalites and drinks) 1, 2, 4, 5, 6, 8, 9, 10, 15

Rule 5 The Ukrainian drinks tea.

solution A.1

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 ivory & milk

4 green & coffee

5 Englishman & red

solution A.2.1

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 Englishman & red & milk

4 ivory

5 green & coffee

solution A.2.2

1 Norwegian & yellow & Kools

2 blue

3 Englishman & red & milk

4 Ukrainian & ivory & tea

5 green & coffee

STEP 6 (look for nationalites or drinks) 1, 2, 3, 4, 5, 6, 8, 9, 10, 15

Rule 3 The Spaniard owns the dog.

solution A.1.1

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 Spaniard & ivory & milk & dog

4 green & coffee

5 Englishman & red

solution A.1.2

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 ivory & milk

4 Spaniard & green & coffee & dog

5 Englishman & red

solution A.2.1.1

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 Englishman & red & milk

4 Spaniard & ivory & dog

5 green & coffee

solution A.2.1.2

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 Englishman & red & milk

4 ivory

5 Spaniard & green & coffee & dog

solution A.2.2.1

1 Norwegian & yellow & Kools

2 Spaniard & blue & dog

3 Englishman & red & milk

4 Ukrainian & ivory & tea

5 green & coffee

solution A.2.2.2

1 Norwegian & yellow & Kools

2 blue

3 Englishman & red & milk

4 Ukrainian & ivory & tea

5 Spaniard & green & coffee & dog

STEP 7 (look for nationalites or drinks) 1, 2, 3, 4, 5, 6, 8, 9, 10, 13, 15

Rule 13 The Lucky Strike smoker drinks orange juice.

solution A.1.1

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 Spaniard & ivory & milk & dog

4 green & coffee

5 Englishman & red & Lucky Strike & orange juice

solution A.1.2

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 ivory & milk

4 Spaniard & green & coffee & dog

5 Englishman & red & Lucky Strike & orange juice

solution A.2.1.1

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 Englishman & red & milk

4 Spaniard & ivory & Lucky Strike & orange juice & dog

5 green & coffee

solution A.2.1.2

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 Englishman & red & milk

4 ivory & Lucky Strike & orange juice

5 Spaniard & green & coffee & dog

solution A.2.2.1

1 Norwegian & yellow & Kools

2 Spaniard & blue & Lucky Strike & orange juice & dog

3 Englishman & red & milk

4 Ukrainian & ivory & tea

5 green & coffee

solution A.2.2.2

1 Norwegian & yellow & Kools

2 blue & Lucky Strike & orange juice

3 Englishman & red & milk

4 Ukrainian & ivory & tea

5 Spaniard & green & coffee & dog

*** At this point we see that in all the possible solutions the remaining drink (water) belongs to group 1 - we’re halfway there

STEP 8 (look for nationalites or drinks) 1, 2, 3, 4, 5, 6, 8, 9, 10, 13, 14, 15

Rule 14 The Japanese smokes Parliaments.

solution A.1.1

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 Spaniard & ivory & milk & dog

4 Japanese & green & Parliaments & coffee

5 Englishman & red & Lucky Strike & orange juice

solution A.1.2

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 Japanese & ivory & Parliaments & milk

4 Spaniard & green & coffee & dog

5 Englishman & red & Lucky Strike & orange juice

solution A.2.1.1

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 Englishman & red & milk

4 Spaniard & ivory & Lucky Strike & orange juice & dog

5 Japanese & green & Parliaments & coffee

solution A.2.1.2 - eliminated!

solution A.2.2.1

1 Norwegian & yellow & Kools

2 Spaniard & blue & Lucky Strike & orange juice & dog

3 Englishman & red & milk

4 Ukrainian & ivory & tea

5 Japanese & green & Parliaments & coffee

solution A.2.2.2 - eliminated!

STEP 9 (going through rest of rules in order) 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14, 15

Rule 7 The Old Gold smoker owns snails.

solution A.1.1

1 Norwegian & yellow & Kools

2 Ukrainian & blue & Old Gold & tea & snails

3 Spaniard & ivory & milk & dog

4 Japanese & green & Parliaments & coffee

5 Englishman & red & Lucky Strike & orange juice

solution A.1.2

1 Norwegian & yellow & Kools

2 Ukrainian & blue & Old Gold & tea & snails

3 Japanese & ivory & Parliaments & milk

4 Spaniard & green & coffee & dog

5 Englishman & red & Lucky Strike & orange juice

solution A.2.1.1.1

1 Norwegian & yellow & Kools

2 Ukrainian & blue & Old Gold & tea & snails

3 Englishman & red & milk

4 Spaniard & ivory & Lucky Strike & orange juice & dog

5 Japanese & green & Parliaments & coffee

solution A.2.1.1.2

1 Norwegian & yellow & Kools

2 Ukrainian & blue & tea

3 Englishman & red & Old Gold & milk & snails

4 Spaniard & ivory & Lucky Strike & orange juice & dog

5 Japanese & green & Parliaments & coffee

solution A.2.2.1.1

1 Norwegian & yellow & Kools

2 Spaniard & blue & Lucky Strike & orange juice & dog

3 Englishman & red & Old Gold & milk & snails

4 Ukrainian & ivory & tea

5 Japanese & green & Parliaments & coffee

solution A.2.2.1.2

1 Norwegian & yellow & Kools

2 Spaniard & blue & Lucky Strike & orange juice & dog

3 Englishman & red & milk

4 Ukrainian & ivory & Old Gold & tea & snails

5 Japanese & green & Parliaments & coffee

STEP 10 (going through rest of rules in order) 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15

Rule 11 The man who smokes Chesterfields lives in the house next to the man with the fox.

solution A.1.1

1 Norwegian & yellow & Kools

2 Ukrainian & blue & Old Gold & tea & snails

3 Spaniard & ivory & Chesterfields & milk & dog

4 Japanese & green & Parliaments & coffee & fox

5 Englishman & red & Lucky Strike & orange juice

solution A.1.2

1 Norwegian & yellow & Kools

2 Ukrainian & blue & Old Gold & tea & snails

3 Japanese & ivory & Parliaments & milk

4 Spaniard & green & Chesterfields & coffee & dog

5 Englishman & red & Lucky Strike & orange juice & fox

solution A.2.1.1.1 - eliminated!

solution A.2.1.1.2

1 Norwegian & yellow & Kools & fox

2 Ukrainian & blue & Chesterfields & tea

3 Englishman & red & Old Gold & milk & snails

4 Spaniard & ivory & Lucky Strike & orange juice & dog

5 Japanese & green & Parliaments & coffee

solution A.2.2.1.1

1 Norwegian & yellow & Kools

2 Spaniard & blue & Lucky Strike & orange juice & dog

3 Englishman & red & Old Gold & milk & snails

4 Ukrainian & ivory & Chesterfields & tea

5 Japanese & green & Parliaments & coffee & fox

solution A.2.2.1.2 - eliminated!

STEP 11 (going through rest of rules in order) 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15

Rule 12 Kools are smoked in the house next to the house where the horse is kept.

solution A.1.1 - eliminated!

solution A.1.2 - eliminated!

solution A.2.1.1.2

1 Norwegian & yellow & Kools & fox

2 Ukrainian & blue & Chesterfields & tea & horse

3 Englishman & red & Old Gold & milk & snails

4 Spaniard & ivory & Lucky Strike & orange juice & dog

5 Japanese & green & Parliaments & coffee

solution A.2.2.1.1 - eliminated!

*** Remaining Animal (Zebra) goes with 5 and drink (water) goes with 1[/spoiler]