From: Rabbi Moshe Sofer
To: Rabbi Eliezer
The Chasam Sofer resolves apparent contradictions among the Lechem Mishneh, Rosh, and Tosfos regarding davar sheyesh lo matirin by establishing a three-way distinction based on whether the permitting path is available to all, to some, or only to someone other than the one prohibited. He further argues that food cooked on Shabbos should be subject to bitul for secondary parties since the cook himself has no matir, and defends the Kesef Mishneh's position that zeh v'zeh gorem does not enable bitul for gidulei terumah.
Source: Shu"t Chasam Sofer YD §223