Substitute For/Of

The answer is "for."
However, that sentence is not well written, and the meaning is not clear.

teechrHowever, that sentence is not well written, and the meaning is not clear.

This is the whole paragraph:

There is no doubt that education and the learning process has changed since the introduction of computers: The search for information has become easier and amusing, and connectivity has expedited the data availability. Though expert syste

I'm fairly certain "for" is the correct word to use there. "Of" makes me think you're talking about a source or characteristic, whereas "for" makes me think you're dealing with "in the place of" (ironically, maybe that's why "of" sounds correct to you).

Examples:
You can substitute honey for sugar. <

the second object here is "sugar"
You can use honey in place of sugar. <

Persian Learner Is the meaning still unclear regarding the surrounding context?

Yes, that text is poorly written.

Persian LearnerThough expert systems have made computers more intelligent, they have not yet become a substitute of

Persian LearnerHi.Though expert systems have made computers more intelligent, they have not yet become a substitute of/for the human interaction in the learning process.Which one is more common?

substitute for [the preposition after substitute is for, not of.]

teechr1- It's not clear what "they" refers to.

Is the ambiguity between computers and expert systems?

Yes.