(E2+E3)/2.

Case 2. Carl's trims are weaker. I.e, if Carl trims X2 to X2' and X3 to X3', such that both X2' and X3' are for him as small as X1, then Bob thinks X1 is still a smallest piece - weakly smaller than X2' and X3'. Then, we proceed as in Case 1, with the roles of Bob and Carl switched.

Case 3. Bob's trim is weaker in X2, and Carl's trim is weaker in X3. I.e, if Bob trims X2 to X2' which is equal to X1 for him, and Carl trims X3 to X3' which is equal to X1 for him, then:
* For Carl: X2' >= X1 = X3'
* For Bob:

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