G2-item #0
Let:
  T1 = {:index 3494, :time 8242172611, :type :ok, :process 167, :f :txn, :value [[:r 135 [1]] [:append 135 10] [:append 134 12] [:r 134 [3 12]]]}
  T2 = {:index 3498, :time 8264595574, :type :ok, :process 141, :f :txn, :value [[:append 135 8] [:append 125 16] [:r 134 nil] [:r 134 nil]]}
  T3 = {:index 3420, :time 8116317589, :type :ok, :process 100, :f :txn, :value [[:append 134 3] [:append 132 7] [:r 133 nil]]}

Then:
  - T1 < T2, because T1 did not observe T2's append of 8 to 135.
  - T2 < T3, because T2 observed the initial (nil) state of 134, which T3 created by appending 3.
  - However, T3 < T1, because T1 appended 12 after T3 appended 3 to 134: a contradiction!