[investigator2100 (OP)]

Prior- knowledge in electromagnetism seems to deal “force between an air-core-solenoid and a permanent magnet”, and   “force between an iron-core-solenoid and a permanent magnet” as the same. On the other hand, many qualified scientists have observed a strange phenomenon. According to them, “permanent magnet attracts the iron-core of a solenoid, too, during repelling”. 
During one of my experiments, the like poles of an iron-core- solenoid and a permanent magnet were set to repel each other. At first, the like poles repelled each other. When both poles had repelled each other to some distance, attraction force was produced subsequently instead of repulsion force. So both poles attracted each other back instead of repelling.

The experiment clearly proves the existence of the attraction during the repulsion. It is obvious that the permanent magnet must first create an unlike pole in the iron-core of the solenoid to attract the core. So the production of attraction between the like poles must mean that a third pole is essentially created between the like poles of an iron-core-solenoid and a permanent magnet. The strange attraction during repulsion is no mystery. It is the effect of the third pole.
 Prior-knowledge does not contain any information about the third pole.
Air-core-solenoids have nothing to do with the third pole because there is no iron core to be influenced.  Iron-core and air-core solenoids are totally different devices when they face a permanent magnet. It is obvious that prior-knowledge is totally inconsistent with the existence of the third pole.
Both poles (created in the iron-core) must interact separately with the permanent magnet because one of the poles is a like pole (in relation to the pole of the permanent magnet) and the other pole of the core is an unlike pole.
As the results of the separate interactions, both attraction and repulsion forces must be produced separately, individually and independently. Both are opposite forces. Each of the force must express itself in parallel. They can never merge into one force.
A  European scientist as a member of a physics research team has observed the third pole. He has very kindly sent me the video of the observation.