There was that boat, over which they were arguing, etc. - ההוא ארבא דהוו מינצו וכולי
Summary:
The view of the ר"ת is that the criteria for יחלוקו are אוחזין and החלוקה יכולה להיות אמת. The view of the ריב"א is that the criteria for יחלוקו is ליכא רמאי or אוחזין (even if איכא רמאי).
Summary:
The רשב"ם maintains that the disputes of תפסינן and מפקינן are dependent on each other, while תוספות maintains they are independent of each other.