Hacham Ovadia ZT"L, in the recently published volume of Yabia Omer, relates an interesting Halacha based on an incident that occurred to him. He was sitting and learning when someone asked him to go to another place to complete a Minyan. He analyzed whether he was obligated to stop his Torah study in order to complete a Minyan. His conclusion was that he does not need to stop learning. Even though the Gemara records that Rabbi Eliezer freed his slave in order to complete a Minyan, thereby violating the Torahs prohibition against doing so, that is not a proof. In that case, the Minyan was assembled in the same place as the slave, but one is not obligate to leave his place to complete a Minyan.
Furthermore, the Sefer Kerach Shel Romi discusses whether one may violate the Rabbinic prohibition of riding a horse on Shabbat in order to attend a Minyan. There, the author presents the importance of attending Minyan, but clearly states that one may not violate Halacha in order to attend. Hacham Ovadia reasons that since Torah learning is the highest Misva, one does not need to stop in order to complete a Minyan for somebody else.
He also discusses an incident in which he was sitting alone eating Seudat Shlishit, and there was also a group of people eating together. He asks whether he was obligated to join their meal in order to partake of Birkat Hamazon with a Zimun, or was he permitted to remain alone in order to finish faster and resume his learning. He concluded that as long as one did not already sit down with them, he is not obligated to go out of his way to put himself in an obligation of Zimun. He cites the Sefer Hasidim who brings that case of someone who does not want to join a group meal out of fear that the meal would carry on too long with idle chatter and rules that one is not obligated to join.
SUMMARY
One is not obligated to interrupt his learning to go to another place and complete a Minyan. Likewise, one may eat alone and avoid joining a Zimun, in order to resume his Torah study.
