- A is sitting at one of the ends of a row.
- B is sitting next to A.
Useful secondary information: Information which does not directly deal with actual seating arrangement, but indirectly help us to understand the situation is called useful secondary information (USI).
- Six people are playing cards.
- Four people are sitting on a bench.
Actual information can be further classified into three subcategories as under:
Definite information or specific information: Information in which the position/place of any person or object is definitely stated is called definite information or specific information.
- B is sitting at the extreme left end of a bench in a park.
- D is sitting second from the right.
In the above statements, positions of B and D are clearly stated.
Comparative information: Information in which the exact place/position of any person or object is not definitely mentioned, but only a comparative position is given, is called comparative information.
- E is sitting next to B.
- A and D are sitting together.
In the above statements, the positions/places of E and B, or A and D, are not definitely known. We know only their comparative or relative positions.
Negative information: Information which denies a particular seating arrangement is called negative information.
- A is not sitting with B.
- C is not sitting at the end of the row.
Though the negative information does not provide any specific information about the seating arrangement, it gives us a clue to eliminate one or more of the possibilities.
- Draw a diagram of empty places. If the people are sitting in a row, draw a horizontal line. Otherwise, draw the diagram as per the specifications given in the problem.
- Using the entire definite information, fill up as many empty places as possible.
- Then examine the comparative information, negative information and USI, if any. After considering all the possibilities and without violating any of the conditions, complete the seating diagram.