diff --git a/prototype/poc-machi/include/machi.hrl b/prototype/poc-machi/include/machi.hrl
index 7a1d969..a7627ed 100644
--- a/prototype/poc-machi/include/machi.hrl
+++ b/prototype/poc-machi/include/machi.hrl
@@ -35,8 +35,6 @@
 -record(projection, {
             epoch_number    :: m_epoch_n(),
             epoch_csum      :: m_csum(),
-            prev_epoch_num  :: m_epoch_n(),
-            prev_epoch_csum :: m_csum(),
             all_members     :: [m_server()],
             down            :: [m_server()],
             creation_time   :: timestamp(),
diff --git a/prototype/poc-machi/src/machi_chain_manager0.erl b/prototype/poc-machi/src/machi_chain_manager0.erl
index e7933ab..c0c3fed 100644
--- a/prototype/poc-machi/src/machi_chain_manager0.erl
+++ b/prototype/poc-machi/src/machi_chain_manager0.erl
@@ -47,12 +47,10 @@ make_initial_projection(MyName, All_list, UPI_list, Repairing_list, Ps) ->
     make_projection(1, 0, <<>>,
                     MyName, All_list, [], UPI_list, Repairing_list, Ps).
 
-make_projection(EpochNum, PrevEpochNum, PrevEpochCSum,
+make_projection(EpochNum, _PrevEpochNum, _PrevEpochCSum,
                 MyName, All_list, Down_list, UPI_list, Repairing_list, Ps) ->
     P = #projection{epoch_number=EpochNum,
                     epoch_csum= <<>>,
-                    prev_epoch_num=PrevEpochNum,
-                    prev_epoch_csum=PrevEpochCSum,
                     creation_time=now(),
                     author_server=MyName,
                     all_members=All_list,
diff --git a/prototype/poc-machi/src/machi_chain_manager1.erl b/prototype/poc-machi/src/machi_chain_manager1.erl
index c770d6c..40fed28 100644
--- a/prototype/poc-machi/src/machi_chain_manager1.erl
+++ b/prototype/poc-machi/src/machi_chain_manager1.erl
@@ -320,23 +320,20 @@ do_read_repair(FLUsRs, _Extra, #ch_mgr{proj=CurrentProj} = S) ->
     end.
 
 make_initial_projection(MyName, All_list, UPI_list, Repairing_list, Ps) ->
-    make_projection(0, -1, <<>>,
-                    MyName, All_list, [], UPI_list, Repairing_list, Ps).
+    make_projection(0, MyName, All_list, [], UPI_list, Repairing_list, Ps).
 
-make_projection(EpochNum, PrevEpochNum, PrevEpochCSum,
+make_projection(EpochNum,
                 MyName, All_list, Down_list, UPI_list, Repairing_list,
                 Dbg) ->
-    make_projection(EpochNum, PrevEpochNum, PrevEpochCSum,
+    make_projection(EpochNum,
                     MyName, All_list, Down_list, UPI_list, Repairing_list,
                     Dbg, []).
 
-make_projection(EpochNum, PrevEpochNum, PrevEpochCSum,
+make_projection(EpochNum,
                 MyName, All_list, Down_list, UPI_list, Repairing_list,
                 Dbg, Dbg2) ->
     P = #projection{epoch_number=EpochNum,
                     epoch_csum= <<>>,           % always checksums as <<>>
-                    prev_epoch_num=PrevEpochNum,
-                    prev_epoch_csum=PrevEpochCSum,
                     creation_time=now(),
                     author_server=MyName,
                     all_members=All_list,
@@ -368,7 +365,6 @@ calc_projection(#ch_mgr{proj=LastProj, runenv=RunEnv} = S, Dbg) ->
 calc_projection(OldThreshold, NoPartitionThreshold, LastProj, Dbg,
                 #ch_mgr{name=MyName, runenv=RunEnv1} = S) ->
     #projection{epoch_number=OldEpochNum,
-                epoch_csum=OldEpochCsum,
                 all_members=All_list,
                 upi=OldUPI_list,
                 repairing=OldRepairing_list
@@ -401,7 +397,7 @@ calc_projection(OldThreshold, NoPartitionThreshold, LastProj, Dbg,
                           NewUp -> Repairing_list3 ++ NewUp
                       end,
     Repairing_list5 = Repairing_list4 -- Down,
-    P = make_projection(OldEpochNum + 1, OldEpochNum, OldEpochCsum,
+    P = make_projection(OldEpochNum + 1,
                         MyName, All_list, Down, NewUPI_list3, Repairing_list5,
                         Dbg ++ [{nodes_up, Up}]),
     {P, S#ch_mgr{runenv=RunEnv3}}.
diff --git a/prototype/poc-machi/test/machi_chain_manager0_test.erl b/prototype/poc-machi/test/machi_chain_manager0_test.erl
index 34f11ad..05eb86e 100644
--- a/prototype/poc-machi/test/machi_chain_manager0_test.erl
+++ b/prototype/poc-machi/test/machi_chain_manager0_test.erl
@@ -222,8 +222,6 @@ projection_transitions_are_sane([P1, P2|T]) ->
 projection_transition_is_sane(
   #projection{epoch_number=Epoch1,
               epoch_csum=CSum1,
-              prev_epoch_num=PrevEpoch1,
-              prev_epoch_csum=PrevCSum1,
               creation_time=CreationTime1,
               author_server=AuthorServer1,
               all_members=All_list1,
@@ -233,8 +231,6 @@ projection_transition_is_sane(
               dbg=Dbg1} = P1,
   #projection{epoch_number=Epoch2,
               epoch_csum=CSum2,
-              prev_epoch_num=PrevEpoch2,
-              prev_epoch_csum=PrevCSum2,
               creation_time=CreationTime2,
               author_server=AuthorServer2,
               all_members=All_list2,
@@ -245,8 +241,6 @@ projection_transition_is_sane(
  try
     true = is_integer(Epoch1) andalso is_integer(Epoch2),
     true = is_binary(CSum1) andalso is_binary(CSum2),
-    true = is_integer(PrevEpoch1) andalso is_integer(PrevEpoch2),
-    true = is_binary(PrevCSum1) andalso is_binary(PrevCSum2),
     {_,_,_} = CreationTime1,
     {_,_,_} = CreationTime2,
     true = is_atom(AuthorServer1) andalso is_atom(AuthorServer2), % todo will probably change
@@ -257,7 +251,6 @@ projection_transition_is_sane(
     true = is_list(Dbg1) andalso is_list(Dbg2),
 
     true = Epoch2 > Epoch1,
-    true = PrevEpoch2 > PrevEpoch1,
     All_list1 = All_list2,                 % todo will probably change
 
     %% No duplicates