@299792458
Hm, so four possibilities so far:
1) Just a whim/interest of his
2) Filling memory/education
3) Finding a clue to Eba
4) Using the knowledge for something
Yeah, I agree with your assessment that 4) or building something would be pretty crazy. From what little I understand, there are some interesting applications, but they would likely require specialized tools and machines to even begin approaching using those concepts, and he doesn't have anything like that with him. The reason I thought of it is because the author pulled the computer vision technology awhile back, so maybe he knows of some obscure new technology that he wanted to pull out here. But I agree that it's definitely unlikely.
I think for either 2) or 1), he could be doing both with the main intent of trying to scout out the current state of technologies, since he wasn't aware of GPS being used commonly, he might be trying to check all sorts of random/advanced fields of study to see if there exists other hypothetical technologies that may be used to track him. I think this one is somewhat likely, and the author probably didn't give too much thought on what books he chose in that case.
3) sounds very possible as well. If he's trying to find Eba, and Eba was a professor who specialized in either of those fields, then perhaps Eba used his own alternate identity in public? So Souichi is looking within those related fields to find out what that identity is? Perhaps trying to find professors who have a writing style similar to his or something.
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About the card, I was thinking he may want to use it to rent a car or something after he leaves Gakuto, since it doesn't seem like he will stay with him for much longer. He can't use any of his own ID because it might be tracked, and he probably needs to start thinking about transportation if he wants to find Eba. I guess it can be used for renting an apartment too, but I imagine other pieces of information are needed for that, I'm not familiar with how it works in Japan however.