In an octagonal company, an engineer, an artilleryman, a herald, an infantryman, and an air officer are present. Among them, there is a centurion, three majors, and a captain. We also know the following about them:

1. Dezso and the engineer are of equal rank.
2. Csongor and the herald are good friends.
3. Csongor was sick last time, Elek and the air officer visited him together.
4. The artilleryman and the engineer bought a radio from the herald on Elek's advice.
5. Csongor wanted to be a pilot, but changed his branch of service on the engineer's advice.

6. Dezso salutes Elek in advance, Bandi salutes Csongor in advance.

Determine which branch of service Antal serves in?
According to the preliminary announcements, only the rank of colonel is held by several people in the company. Thus, from the 1st data point, it is clear that Dezső and the engineer are colonels, and furthermore, that Dezső is not an engineer. According to the 6th data point, on one hand, Elek holds a higher rank than Dezső, so he is the only captain, and therefore he is not an engineer; on the other hand, Bandi holds a lower rank than Csongor - who can only be a colonel - Thus, Bandi is the only captain, so he is not an engineer. Finally, from the 5th data point - among other things - we learn that Csongor is also not an engineer. Therefore, the engineer can only be the one officer not yet mentioned: Antal. This answers the question of the problem.

Wischin Tibor (Bp. VIII., Vörösmarty M. g. I. o. t.)

Remarks. 1. We did not use the 2nd, 3rd, and 4th data points, and from the 5th, we only used this much: "...Csongor ... on the advice of the engineer...", and even from this, we could determine more than necessary: Antal's rank, that he is also a colonel. Based on the superfluous data, it can also be determined that Elek is a captain of infantry, Csongor is a colonel of artillery, but it cannot be decided which of Dezső and Bandi is the herald and which is the flyer.

Gálfi László (Bp. VIII., Fazekas M. g. I. o. t.)

2. That some of the announcements were superfluous is in agreement with the fact that in life, we often learn things for which we have no need, either for a specific purpose or at all. Part of solving a problem is the selection process by which we retain the necessary data and discard the superfluous ones.