TSTP Solution File: SEU103+1 by Otter---3.3
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- Process Solution
%------------------------------------------------------------------------------
% File : Otter---3.3
% Problem : SEU103+1 : TPTP v8.1.0. Released v3.2.0.
% Transfm : none
% Format : tptp:raw
% Command : otter-tptp-script %s
% Computer : n023.cluster.edu
% Model : x86_64 x86_64
% CPU : Intel(R) Xeon(R) CPU E5-2620 v4 2.10GHz
% Memory : 8042.1875MB
% OS : Linux 3.10.0-693.el7.x86_64
% CPULimit : 300s
% WCLimit : 300s
% DateTime : Wed Jul 27 13:14:46 EDT 2022
% Result : Timeout 299.91s 300.03s
% Output : None
% Verified :
% SZS Type : -
% Comments :
%------------------------------------------------------------------------------
%----No solution output by system
%------------------------------------------------------------------------------
%----ORIGINAL SYSTEM OUTPUT
% 0.07/0.12 % Problem : SEU103+1 : TPTP v8.1.0. Released v3.2.0.
% 0.07/0.13 % Command : otter-tptp-script %s
% 0.13/0.34 % Computer : n023.cluster.edu
% 0.13/0.34 % Model : x86_64 x86_64
% 0.13/0.34 % CPU : Intel(R) Xeon(R) CPU E5-2620 v4 @ 2.10GHz
% 0.13/0.34 % Memory : 8042.1875MB
% 0.13/0.34 % OS : Linux 3.10.0-693.el7.x86_64
% 0.13/0.34 % CPULimit : 300
% 0.13/0.34 % WCLimit : 300
% 0.13/0.34 % DateTime : Wed Jul 27 08:01:48 EDT 2022
% 0.13/0.34 % CPUTime :
% 2.21/2.36 ----- Otter 3.3f, August 2004 -----
% 2.21/2.36 The process was started by sandbox2 on n023.cluster.edu,
% 2.21/2.36 Wed Jul 27 08:01:48 2022
% 2.21/2.36 The command was "./otter". The process ID is 26623.
% 2.21/2.36
% 2.21/2.36 set(prolog_style_variables).
% 2.21/2.36 set(auto).
% 2.21/2.36 dependent: set(auto1).
% 2.21/2.36 dependent: set(process_input).
% 2.21/2.36 dependent: clear(print_kept).
% 2.21/2.36 dependent: clear(print_new_demod).
% 2.21/2.36 dependent: clear(print_back_demod).
% 2.21/2.36 dependent: clear(print_back_sub).
% 2.21/2.36 dependent: set(control_memory).
% 2.21/2.36 dependent: assign(max_mem, 12000).
% 2.21/2.36 dependent: assign(pick_given_ratio, 4).
% 2.21/2.36 dependent: assign(stats_level, 1).
% 2.21/2.36 dependent: assign(max_seconds, 10800).
% 2.21/2.36 clear(print_given).
% 2.21/2.36
% 2.21/2.36 formula_list(usable).
% 2.21/2.36 all A (A=A).
% 2.21/2.36 all A B (in(A,B)-> -in(B,A)).
% 2.21/2.36 all A (empty(A)->finite(A)).
% 2.21/2.36 all A (preboolean(A)->cup_closed(A)&diff_closed(A)).
% 2.21/2.36 all A (finite(A)-> (all B (element(B,powerset(A))->finite(B)))).
% 2.21/2.36 all A (cup_closed(A)&diff_closed(A)->preboolean(A)).
% 2.21/2.36 all A B C (-empty(A)&preboolean(A)&element(B,A)&element(C,A)->prebool_union2(A,B,C)=prebool_union2(A,C,B)).
% 2.21/2.36 all A B (set_union2(A,B)=set_union2(B,A)).
% 2.21/2.36 all A B (symmetric_difference(A,B)=symmetric_difference(B,A)).
% 2.21/2.36 all A B (symmetric_difference(A,B)=set_union2(set_difference(A,B),set_difference(B,A))).
% 2.21/2.36 all A B C (-empty(A)&preboolean(A)&element(B,A)&element(C,A)->element(prebool_union2(A,B,C),A)).
% 2.21/2.36 all A B C (-empty(A)&preboolean(A)&element(B,A)&element(C,A)->element(prebool_difference(A,B,C),A)).
% 2.21/2.36 all A exists B element(B,A).
% 2.21/2.36 all A B (finite(A)->finite(set_difference(A,B))).
% 2.21/2.36 all A B (finite(A)&finite(B)->finite(symmetric_difference(A,B))).
% 2.21/2.36 all A (-empty(powerset(A))).
% 2.21/2.36 empty(empty_set).
% 2.21/2.36 all A B (-empty(A)-> -empty(set_union2(A,B))).
% 2.21/2.36 all A B (-empty(A)-> -empty(set_union2(B,A))).
% 2.21/2.36 all A B (finite(A)&finite(B)->finite(set_union2(A,B))).
% 2.21/2.36 all A B C (-empty(A)&preboolean(A)&element(B,A)&element(C,A)->prebool_union2(A,B,B)=B).
% 2.21/2.36 all A B (set_union2(A,A)=A).
% 2.21/2.36 exists A (-empty(A)&finite(A)).
% 2.21/2.36 exists A (-empty(A)&cup_closed(A)&cap_closed(A)&diff_closed(A)&preboolean(A)).
% 2.21/2.36 all A (-empty(A)-> (exists B (element(B,powerset(A))& -empty(B)))).
% 2.21/2.36 exists A empty(A).
% 2.21/2.36 all A exists B (element(B,powerset(A))&empty(B)&relation(B)&function(B)&one_to_one(B)&epsilon_transitive(B)&epsilon_connected(B)&ordinal(B)&natural(B)&finite(B)).
% 2.21/2.36 all A exists B (element(B,powerset(A))&empty(B)).
% 2.21/2.36 exists A (-empty(A)).
% 2.21/2.36 all A (-empty(A)-> (exists B (element(B,powerset(A))& -empty(B)&finite(B)))).
% 2.21/2.36 all A (-empty(A)-> (exists B (element(B,powerset(A))& -empty(B)&finite(B)))).
% 2.21/2.36 all A B C (-empty(A)&preboolean(A)&element(B,A)&element(C,A)->prebool_union2(A,B,C)=set_union2(B,C)).
% 2.21/2.36 all A B C (-empty(A)&preboolean(A)&element(B,A)&element(C,A)->prebool_difference(A,B,C)=set_difference(B,C)).
% 2.21/2.36 all A B subset(A,A).
% 2.21/2.36 -(all A B C (-empty(C)&preboolean(C)-> (element(A,C)&element(B,C)->element(symmetric_difference(A,B),C)))).
% 2.21/2.36 all A (set_union2(A,empty_set)=A).
% 2.21/2.36 all A B (in(A,B)->element(A,B)).
% 2.21/2.36 all A B (element(A,B)->empty(B)|in(A,B)).
% 2.21/2.36 all A (set_difference(A,empty_set)=A).
% 2.21/2.36 all A B (element(A,powerset(B))<->subset(A,B)).
% 2.21/2.36 all A (set_difference(empty_set,A)=empty_set).
% 2.21/2.36 all A B C (in(A,B)&element(B,powerset(C))->element(A,C)).
% 2.21/2.36 all A (symmetric_difference(A,empty_set)=A).
% 2.21/2.36 all A B C (-(in(A,B)&element(B,powerset(C))&empty(C))).
% 2.21/2.36 all A (empty(A)->A=empty_set).
% 2.21/2.36 all A B (-(in(A,B)&empty(B))).
% 2.21/2.36 all A B (-(empty(A)&A!=B&empty(B))).
% 2.21/2.36 end_of_list.
% 2.21/2.36
% 2.21/2.36 -------> usable clausifies to:
% 2.21/2.36
% 2.21/2.36 list(usable).
% 2.21/2.36 0 [] A=A.
% 2.21/2.36 0 [] -in(A,B)| -in(B,A).
% 2.21/2.36 0 [] -empty(A)|finite(A).
% 2.21/2.36 0 [] -preboolean(A)|cup_closed(A).
% 2.21/2.36 0 [] -preboolean(A)|diff_closed(A).
% 2.21/2.36 0 [] -finite(A)| -element(B,powerset(A))|finite(B).
% 2.21/2.36 0 [] -cup_closed(A)| -diff_closed(A)|preboolean(A).
% 2.21/2.36 0 [] empty(A)| -preboolean(A)| -element(B,A)| -element(C,A)|prebool_union2(A,B,C)=prebool_union2(A,C,B).
% 2.21/2.36 0 [] set_union2(A,B)=set_union2(B,A).
% 2.21/2.36 0 [] symmetric_difference(A,B)=symmetric_difference(B,A).
% 2.21/2.36 0 [] symmetric_difference(A,B)=set_union2(set_difference(A,B),set_difference(B,A)).
% 2.21/2.36 0 [] empty(A)| -preboolean(A)| -element(B,A)| -element(C,A)|element(prebool_union2(A,B,C),A).
% 2.21/2.36 0 [] empty(A)| -preboolean(A)| -element(B,A)| -element(C,A)|element(prebool_difference(A,B,C),A).
% 2.21/2.36 0 [] element($f1(A),A).
% 2.21/2.36 0 [] -finite(A)|finite(set_difference(A,B)).
% 2.21/2.36 0 [] -finite(A)| -finite(B)|finite(symmetric_difference(A,B)).
% 2.21/2.36 0 [] -empty(powerset(A)).
% 2.21/2.36 0 [] empty(empty_set).
% 2.21/2.36 0 [] empty(A)| -empty(set_union2(A,B)).
% 2.21/2.36 0 [] empty(A)| -empty(set_union2(B,A)).
% 2.21/2.36 0 [] -finite(A)| -finite(B)|finite(set_union2(A,B)).
% 2.21/2.36 0 [] empty(A)| -preboolean(A)| -element(B,A)| -element(C,A)|prebool_union2(A,B,B)=B.
% 2.21/2.36 0 [] set_union2(A,A)=A.
% 2.21/2.36 0 [] -empty($c1).
% 2.21/2.36 0 [] finite($c1).
% 2.21/2.36 0 [] -empty($c2).
% 2.21/2.36 0 [] cup_closed($c2).
% 2.21/2.36 0 [] cap_closed($c2).
% 2.21/2.36 0 [] diff_closed($c2).
% 2.21/2.36 0 [] preboolean($c2).
% 2.21/2.36 0 [] empty(A)|element($f2(A),powerset(A)).
% 2.21/2.36 0 [] empty(A)| -empty($f2(A)).
% 2.21/2.36 0 [] empty($c3).
% 2.21/2.36 0 [] element($f3(A),powerset(A)).
% 2.21/2.36 0 [] empty($f3(A)).
% 2.21/2.36 0 [] relation($f3(A)).
% 2.21/2.36 0 [] function($f3(A)).
% 2.21/2.36 0 [] one_to_one($f3(A)).
% 2.21/2.36 0 [] epsilon_transitive($f3(A)).
% 2.21/2.36 0 [] epsilon_connected($f3(A)).
% 2.21/2.36 0 [] ordinal($f3(A)).
% 2.21/2.36 0 [] natural($f3(A)).
% 2.21/2.36 0 [] finite($f3(A)).
% 2.21/2.36 0 [] element($f4(A),powerset(A)).
% 2.21/2.36 0 [] empty($f4(A)).
% 2.21/2.36 0 [] -empty($c4).
% 2.21/2.36 0 [] empty(A)|element($f5(A),powerset(A)).
% 2.21/2.36 0 [] empty(A)| -empty($f5(A)).
% 2.21/2.36 0 [] empty(A)|finite($f5(A)).
% 2.21/2.36 0 [] empty(A)|element($f6(A),powerset(A)).
% 2.21/2.36 0 [] empty(A)| -empty($f6(A)).
% 2.21/2.36 0 [] empty(A)|finite($f6(A)).
% 2.21/2.36 0 [] empty(A)| -preboolean(A)| -element(B,A)| -element(C,A)|prebool_union2(A,B,C)=set_union2(B,C).
% 2.21/2.36 0 [] empty(A)| -preboolean(A)| -element(B,A)| -element(C,A)|prebool_difference(A,B,C)=set_difference(B,C).
% 2.21/2.36 0 [] subset(A,A).
% 2.21/2.36 0 [] -empty($c5).
% 2.21/2.36 0 [] preboolean($c5).
% 2.21/2.36 0 [] element($c7,$c5).
% 2.21/2.36 0 [] element($c6,$c5).
% 2.21/2.36 0 [] -element(symmetric_difference($c7,$c6),$c5).
% 2.21/2.36 0 [] set_union2(A,empty_set)=A.
% 2.21/2.36 0 [] -in(A,B)|element(A,B).
% 2.21/2.36 0 [] -element(A,B)|empty(B)|in(A,B).
% 2.21/2.36 0 [] set_difference(A,empty_set)=A.
% 2.21/2.36 0 [] -element(A,powerset(B))|subset(A,B).
% 2.21/2.36 0 [] element(A,powerset(B))| -subset(A,B).
% 2.21/2.36 0 [] set_difference(empty_set,A)=empty_set.
% 2.21/2.36 0 [] -in(A,B)| -element(B,powerset(C))|element(A,C).
% 2.21/2.36 0 [] symmetric_difference(A,empty_set)=A.
% 2.21/2.36 0 [] -in(A,B)| -element(B,powerset(C))| -empty(C).
% 2.21/2.36 0 [] -empty(A)|A=empty_set.
% 2.21/2.36 0 [] -in(A,B)| -empty(B).
% 2.21/2.36 0 [] -empty(A)|A=B| -empty(B).
% 2.21/2.36 end_of_list.
% 2.21/2.36
% 2.21/2.36 SCAN INPUT: prop=0, horn=0, equality=1, symmetry=0, max_lits=5.
% 2.21/2.36
% 2.21/2.36 This ia a non-Horn set with equality. The strategy will be
% 2.21/2.36 Knuth-Bendix, ordered hyper_res, factoring, and unit
% 2.21/2.36 deletion, with positive clauses in sos and nonpositive
% 2.21/2.36 clauses in usable.
% 2.21/2.36
% 2.21/2.36 dependent: set(knuth_bendix).
% 2.21/2.36 dependent: set(anl_eq).
% 2.21/2.36 dependent: set(para_from).
% 2.21/2.36 dependent: set(para_into).
% 2.21/2.36 dependent: clear(para_from_right).
% 2.21/2.36 dependent: clear(para_into_right).
% 2.21/2.36 dependent: set(para_from_vars).
% 2.21/2.36 dependent: set(eq_units_both_ways).
% 2.21/2.36 dependent: set(dynamic_demod_all).
% 2.21/2.36 dependent: set(dynamic_demod).
% 2.21/2.36 dependent: set(order_eq).
% 2.21/2.36 dependent: set(back_demod).
% 2.21/2.36 dependent: set(lrpo).
% 2.21/2.36 dependent: set(hyper_res).
% 2.21/2.36 dependent: set(unit_deletion).
% 2.21/2.36 dependent: set(factor).
% 2.21/2.36
% 2.21/2.36 ------------> process usable:
% 2.21/2.36 ** KEPT (pick-wt=6): 1 [] -in(A,B)| -in(B,A).
% 2.21/2.36 ** KEPT (pick-wt=4): 2 [] -empty(A)|finite(A).
% 2.21/2.36 ** KEPT (pick-wt=4): 3 [] -preboolean(A)|cup_closed(A).
% 2.21/2.36 ** KEPT (pick-wt=4): 4 [] -preboolean(A)|diff_closed(A).
% 2.21/2.36 ** KEPT (pick-wt=8): 5 [] -finite(A)| -element(B,powerset(A))|finite(B).
% 2.21/2.36 ** KEPT (pick-wt=6): 6 [] -cup_closed(A)| -diff_closed(A)|preboolean(A).
% 2.21/2.36 ** KEPT (pick-wt=19): 7 [] empty(A)| -preboolean(A)| -element(B,A)| -element(C,A)|prebool_union2(A,B,C)=prebool_union2(A,C,B).
% 2.21/2.36 ** KEPT (pick-wt=16): 8 [] empty(A)| -preboolean(A)| -element(B,A)| -element(C,A)|element(prebool_union2(A,B,C),A).
% 2.21/2.36 ** KEPT (pick-wt=16): 9 [] empty(A)| -preboolean(A)| -element(B,A)| -element(C,A)|element(prebool_difference(A,B,C),A).
% 2.21/2.36 ** KEPT (pick-wt=6): 10 [] -finite(A)|finite(set_difference(A,B)).
% 2.21/2.36 ** KEPT (pick-wt=8): 11 [] -finite(A)| -finite(B)|finite(symmetric_difference(A,B)).
% 2.21/2.36 ** KEPT (pick-wt=3): 12 [] -empty(powerset(A)).
% 2.21/2.36 ** KEPT (pick-wt=6): 13 [] empty(A)| -empty(set_union2(A,B)).
% 2.21/2.36 ** KEPT (pick-wt=6): 14 [] empty(A)| -empty(set_union2(B,A)).
% 2.21/2.36 ** KEPT (pick-wt=8): 15 [] -finite(A)| -finite(B)|finite(set_union2(A,B)).
% 2.21/2.36 ** KEPT (pick-wt=13): 17 [copy,16,factor_simp] empty(A)| -preboolean(A)| -element(B,A)|prebool_union2(A,B,B)=B.
% 2.21/2.36 ** KEPT (pick-wt=2): 18 [] -empty($c1).
% 2.21/2.36 ** KEPT (pick-wt=2): 19 [] -empty($c2).
% 2.21/2.36 ** KEPT (pick-wt=5): 20 [] empty(A)| -empty($f2(A)).
% 2.21/2.36 ** KEPT (pick-wt=2): 21 [] -empty($c4).
% 2.21/2.36 ** KEPT (pick-wt=5): 22 [] empty(A)| -empty($f5(A)).
% 2.21/2.36 ** KEPT (pick-wt=5): 23 [] empty(A)| -empty($f6(A)).
% 2.21/2.36 ** KEPT (pick-wt=18): 24 [] empty(A)| -preboolean(A)| -element(B,A)| -element(C,A)|prebool_union2(A,B,C)=set_union2(B,C).
% 2.21/2.36 ** KEPT (pick-wt=18): 25 [] empty(A)| -preboolean(A)| -element(B,A)| -element(C,A)|prebool_difference(A,B,C)=set_difference(B,C).
% 2.21/2.36 ** KEPT (pick-wt=2): 26 [] -empty($c5).
% 2.21/2.36 ** KEPT (pick-wt=5): 27 [] -element(symmetric_difference($c7,$c6),$c5).
% 2.21/2.36 ** KEPT (pick-wt=6): 28 [] -in(A,B)|element(A,B).
% 2.21/2.36 ** KEPT (pick-wt=8): 29 [] -element(A,B)|empty(B)|in(A,B).
% 2.21/2.36 ** KEPT (pick-wt=7): 30 [] -element(A,powerset(B))|subset(A,B).
% 2.21/2.36 ** KEPT (pick-wt=7): 31 [] element(A,powerset(B))| -subset(A,B).
% 2.21/2.36 ** KEPT (pick-wt=10): 32 [] -in(A,B)| -element(B,powerset(C))|element(A,C).
% 2.21/2.36 ** KEPT (pick-wt=9): 33 [] -in(A,B)| -element(B,powerset(C))| -empty(C).
% 2.21/2.36 ** KEPT (pick-wt=5): 34 [] -empty(A)|A=empty_set.
% 2.21/2.36 ** KEPT (pick-wt=5): 35 [] -in(A,B)| -empty(B).
% 2.21/2.36 ** KEPT (pick-wt=7): 36 [] -empty(A)|A=B| -empty(B).
% 2.21/2.36
% 2.21/2.36 ------------> process sos:
% 2.21/2.36 ** KEPT (pick-wt=3): 46 [] A=A.
% 2.21/2.36 ** KEPT (pick-wt=7): 47 [] set_union2(A,B)=set_union2(B,A).
% 2.21/2.36 ** KEPT (pick-wt=7): 48 [] symmetric_difference(A,B)=symmetric_difference(B,A).
% 2.21/2.36 ** KEPT (pick-wt=11): 49 [] symmetric_difference(A,B)=set_union2(set_difference(A,B),set_difference(B,A)).
% 2.21/2.36 ---> New Demodulator: 50 [new_demod,49] symmetric_difference(A,B)=set_union2(set_difference(A,B),set_difference(B,A)).
% 2.21/2.36 ** KEPT (pick-wt=4): 51 [] element($f1(A),A).
% 2.21/2.36 ** KEPT (pick-wt=2): 52 [] empty(empty_set).
% 2.21/2.36 ** KEPT (pick-wt=5): 53 [] set_union2(A,A)=A.
% 2.21/2.36 ---> New Demodulator: 54 [new_demod,53] set_union2(A,A)=A.
% 2.21/2.36 ** KEPT (pick-wt=2): 55 [] finite($c1).
% 2.21/2.36 ** KEPT (pick-wt=2): 56 [] cup_closed($c2).
% 2.21/2.36 ** KEPT (pick-wt=2): 57 [] cap_closed($c2).
% 2.21/2.36 ** KEPT (pick-wt=2): 58 [] diff_closed($c2).
% 2.21/2.36 ** KEPT (pick-wt=2): 59 [] preboolean($c2).
% 2.21/2.36 ** KEPT (pick-wt=7): 60 [] empty(A)|element($f2(A),powerset(A)).
% 2.21/2.36 ** KEPT (pick-wt=2): 61 [] empty($c3).
% 2.21/2.36 ** KEPT (pick-wt=5): 62 [] element($f3(A),powerset(A)).
% 2.21/2.36 ** KEPT (pick-wt=3): 63 [] empty($f3(A)).
% 2.21/2.36 ** KEPT (pick-wt=3): 64 [] relation($f3(A)).
% 2.21/2.36 ** KEPT (pick-wt=3): 65 [] function($f3(A)).
% 2.21/2.36 ** KEPT (pick-wt=3): 66 [] one_to_one($f3(A)).
% 2.21/2.36 ** KEPT (pick-wt=3): 67 [] epsilon_transitive($f3(A)).
% 2.21/2.36 ** KEPT (pick-wt=3): 68 [] epsilon_connected($f3(A)).
% 2.21/2.36 ** KEPT (pick-wt=3): 69 [] ordinal($f3(A)).
% 2.21/2.36 ** KEPT (pick-wt=3): 70 [] natural($f3(A)).
% 2.21/2.36 ** KEPT (pick-wt=3): 71 [] finite($f3(A)).
% 2.21/2.36 ** KEPT (pick-wt=5): 72 [] element($f4(A),powerset(A)).
% 2.21/2.36 ** KEPT (pick-wt=3): 73 [] empty($f4(A)).
% 2.21/2.36 ** KEPT (pick-wt=7): 74 [] empty(A)|element($f5(A),powerset(A)).
% 2.21/2.36 ** KEPT (pick-wt=5): 75 [] empty(A)|finite($f5(A)).
% 2.21/2.36 ** KEPT (pick-wt=7): 76 [] empty(A)|element($f6(A),powerset(A)).
% 2.21/2.36 ** KEPT (pick-wt=5): 77 [] empty(A)|finite($f6(A)).
% 2.21/2.36 ** KEPT (pick-wt=3): 78 [] subset(A,A).
% 2.21/2.36 ** KEPT (pick-wt=2): 79 [] preboolean($c5).
% 2.21/2.36 ** KEPT (pick-wt=3): 80 [] element($c7,$c5).
% 2.21/2.36 ** KEPT (pick-wt=3): 81 [] element($c6,$c5).
% 2.21/2.36 ** KEPT (pick-wt=5): 82 [] set_union2(A,empty_set)=A.
% 2.21/2.36 ---> New Demodulator: 83 [new_demod,82] set_union2(A,empty_set)=A.
% 2.21/2.36 ** KEPT (pick-wt=5): 84 [] set_difference(A,empty_set)=A.
% 2.21/2.36 ---> New Demodulator: 85 [new_demod,84] set_difference(A,empty_set)=A.
% 2.21/2.36 ** KEPT (pick-wt=5): 86 [] set_difference(empty_set,A)=empty_set.
% 2.21/2.36 ---> New Demodulator: 87 [new_demod,86] set_difference(empty_set,A)=empty_set.
% 2.21/2.36 Following clause subsumed by 46 during input processing: 0 [demod,50,85,87,83] A=A.
% 2.21/2.36 Following clause subsumed by 46 during input processing: 0 [copy,46,flip.1] A=A.
% 2.21/2.36 46 back subsumes 45.
% 2.21/2.36 46 back subsumes 38.
% 2.21/2.36 Following clause subsumed by 47 during input processing: 0 [copy,47,flip.1] set_union2(A,B)=set_union2(B,A).
% 2.21/2.36 Following clause subsumed by 47 during input processing: 0 [copy,48,flip.1,demod,50,50] set_union2(set_difference(A,B),set_difference(B,A))=set_union2(set_difference(B,A),set_difference(A,B)).
% 2.21/2.36 >>>> Starting back demodulation with 50.
% 2.21/2.36 >> back demodulating 48 with 50.
% 2.21/2.36 >> back demodulating 41 with 50.
% 2.21/2.36 Alarm clock
% 299.91/300.03 Otter interrupted
% 299.91/300.03 PROOF NOT FOUND
%------------------------------------------------------------------------------