Avery , Blake , Clark and Doyle each live in an apartment. Their apartment are arranged like this :

+---+---+---+---+
| A | B | C | D | **-->** East
+---+---+---+---+

- One of the four is the landlord.
- If Clark's apartment is not next to Blake's apartment, then the landlord is Avery & lives in apartment A.
- If Avery's apartment is east of Clark's apartment, then the landlord is Doyle and lives in apartment D.
- If Blake's apartment is not next to Doyle's apartment, then the landlord is Clark and lives in apartment C.
- If Doyle's apartment is east of Avery's apartment, then the landlord is Blake and lives in apartment B.

Who is the landlord?

I agree with Ady. The only solution is DACB. I solved this by forming the contrapositives of statements 2 - 5, figuring that 3 or 4 of the following predicates need to be true

2. C is next to B

3. A is west of C

4. B is next to D

5. D is west of A

and then logicking out that 4 was false.

But it is almost easier just to list the 24 possible combinations

ABCD -- This makes both B & C the landlord, which contradicts 1

ABDC -- This makes both A & B the landlord, which contradicts 1

ACBD -- contradicts 5

ACDB -- contradicts 5

ADBC -- contradicts 5

ADCB -- contradicts 4

BACD -- contradicts 2

BADC -- contradicts 2

BCAD -- contradicts 4

BCDA -- contradicts 3

BDAC -- contradicts 2

BDCA -- contradicts 2

CABD -- contradicts 2

CADB -- contradicts 2

CBAD -- contradicts 4

CBDA -- contradicts 3

CDAB -- contradicts 2

CDBA -- contradicts 2

DABC -- contradicts 4

**DACB -- solution**

DBAC -- contradicts 2

DBCA -- contradicts 3

DCAB -- contradicts 2

DCBA -- contradicts 3

Good puzzle. Not a D1.