/export/starexec/sandbox2/solver/bin/starexec_run_complexity /export/starexec/sandbox2/benchmark/theBenchmark.xml /export/starexec/sandbox2/output/output_files -------------------------------------------------------------------------------- WORST_CASE(Omega(n^1), O(n^2)) proof of /export/starexec/sandbox2/benchmark/theBenchmark.xml # AProVE Commit ID: 794c25de1cacf0d048858bcd21c9a779e1221865 marcel 20200619 unpublished dirty The Runtime Complexity (full) of the given CpxTRS could be proven to be BOUNDS(n^1, n^2). (0) CpxTRS (1) RcToIrcProof [BOTH BOUNDS(ID, ID), 0 ms] (2) CpxTRS (3) RelTrsToWeightedTrsProof [BOTH BOUNDS(ID, ID), 0 ms] (4) CpxWeightedTrs (5) TypeInferenceProof [BOTH BOUNDS(ID, ID), 0 ms] (6) CpxTypedWeightedTrs (7) CompletionProof [UPPER BOUND(ID), 0 ms] (8) CpxTypedWeightedCompleteTrs (9) CpxTypedWeightedTrsToRntsProof [UPPER BOUND(ID), 0 ms] (10) CpxRNTS (11) CompleteCoflocoProof [FINISHED, 316 ms] (12) BOUNDS(1, n^2) (13) RenamingProof [BOTH BOUNDS(ID, ID), 0 ms] (14) CpxTRS (15) SlicingProof [LOWER BOUND(ID), 0 ms] (16) CpxTRS (17) TypeInferenceProof [BOTH BOUNDS(ID, ID), 0 ms] (18) typed CpxTrs (19) OrderProof [LOWER BOUND(ID), 0 ms] (20) typed CpxTrs (21) RewriteLemmaProof [LOWER BOUND(ID), 250 ms] (22) BEST (23) proven lower bound (24) LowerBoundPropagationProof [FINISHED, 0 ms] (25) BOUNDS(n^1, INF) (26) typed CpxTrs ---------------------------------------- (0) Obligation: The Runtime Complexity (full) of the given CpxTRS could be proven to be BOUNDS(n^1, n^2). The TRS R consists of the following rules: lt(0, s(x)) -> true lt(x, 0) -> false lt(s(x), s(y)) -> lt(x, y) fac(x) -> help(x, 0) help(x, c) -> if(lt(c, x), x, c) if(true, x, c) -> times(s(c), help(x, s(c))) if(false, x, c) -> s(0) S is empty. Rewrite Strategy: FULL ---------------------------------------- (1) RcToIrcProof (BOTH BOUNDS(ID, ID)) Converted rc-obligation to irc-obligation. The duplicating contexts are: help(x, []) help([], c) if(true, x, []) The defined contexts are: if([], x1, x2) [] just represents basic- or constructor-terms in the following defined contexts: if([], x1, x2) As the TRS is an overlay system and the defined contexts and the duplicating contexts don't overlap, we have rc = irc. ---------------------------------------- (2) Obligation: The Runtime Complexity (innermost) of the given CpxTRS could be proven to be BOUNDS(1, n^2). The TRS R consists of the following rules: lt(0, s(x)) -> true lt(x, 0) -> false lt(s(x), s(y)) -> lt(x, y) fac(x) -> help(x, 0) help(x, c) -> if(lt(c, x), x, c) if(true, x, c) -> times(s(c), help(x, s(c))) if(false, x, c) -> s(0) S is empty. Rewrite Strategy: INNERMOST ---------------------------------------- (3) RelTrsToWeightedTrsProof (BOTH BOUNDS(ID, ID)) Transformed relative TRS to weighted TRS ---------------------------------------- (4) Obligation: The Runtime Complexity (innermost) of the given CpxWeightedTrs could be proven to be BOUNDS(1, n^2). The TRS R consists of the following rules: lt(0, s(x)) -> true [1] lt(x, 0) -> false [1] lt(s(x), s(y)) -> lt(x, y) [1] fac(x) -> help(x, 0) [1] help(x, c) -> if(lt(c, x), x, c) [1] if(true, x, c) -> times(s(c), help(x, s(c))) [1] if(false, x, c) -> s(0) [1] Rewrite Strategy: INNERMOST ---------------------------------------- (5) TypeInferenceProof (BOTH BOUNDS(ID, ID)) Infered types. ---------------------------------------- (6) Obligation: Runtime Complexity Weighted TRS with Types. The TRS R consists of the following rules: lt(0, s(x)) -> true [1] lt(x, 0) -> false [1] lt(s(x), s(y)) -> lt(x, y) [1] fac(x) -> help(x, 0) [1] help(x, c) -> if(lt(c, x), x, c) [1] if(true, x, c) -> times(s(c), help(x, s(c))) [1] if(false, x, c) -> s(0) [1] The TRS has the following type information: lt :: 0:s:times -> 0:s:times -> true:false 0 :: 0:s:times s :: 0:s:times -> 0:s:times true :: true:false false :: true:false fac :: 0:s:times -> 0:s:times help :: 0:s:times -> 0:s:times -> 0:s:times if :: true:false -> 0:s:times -> 0:s:times -> 0:s:times times :: 0:s:times -> 0:s:times -> 0:s:times Rewrite Strategy: INNERMOST ---------------------------------------- (7) CompletionProof (UPPER BOUND(ID)) The TRS is a completely defined constructor system, as every type has a constant constructor and the following rules were added: lt(v0, v1) -> null_lt [0] if(v0, v1, v2) -> null_if [0] And the following fresh constants: null_lt, null_if ---------------------------------------- (8) Obligation: Runtime Complexity Weighted TRS where all functions are completely defined. The underlying TRS is: Runtime Complexity Weighted TRS with Types. The TRS R consists of the following rules: lt(0, s(x)) -> true [1] lt(x, 0) -> false [1] lt(s(x), s(y)) -> lt(x, y) [1] fac(x) -> help(x, 0) [1] help(x, c) -> if(lt(c, x), x, c) [1] if(true, x, c) -> times(s(c), help(x, s(c))) [1] if(false, x, c) -> s(0) [1] lt(v0, v1) -> null_lt [0] if(v0, v1, v2) -> null_if [0] The TRS has the following type information: lt :: 0:s:times:null_if -> 0:s:times:null_if -> true:false:null_lt 0 :: 0:s:times:null_if s :: 0:s:times:null_if -> 0:s:times:null_if true :: true:false:null_lt false :: true:false:null_lt fac :: 0:s:times:null_if -> 0:s:times:null_if help :: 0:s:times:null_if -> 0:s:times:null_if -> 0:s:times:null_if if :: true:false:null_lt -> 0:s:times:null_if -> 0:s:times:null_if -> 0:s:times:null_if times :: 0:s:times:null_if -> 0:s:times:null_if -> 0:s:times:null_if null_lt :: true:false:null_lt null_if :: 0:s:times:null_if Rewrite Strategy: INNERMOST ---------------------------------------- (9) CpxTypedWeightedTrsToRntsProof (UPPER BOUND(ID)) Transformed the TRS into an over-approximating RNTS by (improved) Size Abstraction. The constant constructors are abstracted as follows: 0 => 0 true => 2 false => 1 null_lt => 0 null_if => 0 ---------------------------------------- (10) Obligation: Complexity RNTS consisting of the following rules: fac(z) -{ 1 }-> help(x, 0) :|: x >= 0, z = x help(z, z') -{ 1 }-> if(lt(c, x), x, c) :|: c >= 0, x >= 0, z' = c, z = x if(z, z', z'') -{ 0 }-> 0 :|: v0 >= 0, z'' = v2, v1 >= 0, z = v0, z' = v1, v2 >= 0 if(z, z', z'') -{ 1 }-> 1 + 0 :|: z' = x, c >= 0, z = 1, x >= 0, z'' = c if(z, z', z'') -{ 1 }-> 1 + (1 + c) + help(x, 1 + c) :|: z = 2, z' = x, c >= 0, x >= 0, z'' = c lt(z, z') -{ 1 }-> lt(x, y) :|: z' = 1 + y, x >= 0, y >= 0, z = 1 + x lt(z, z') -{ 1 }-> 2 :|: z' = 1 + x, x >= 0, z = 0 lt(z, z') -{ 1 }-> 1 :|: x >= 0, z = x, z' = 0 lt(z, z') -{ 0 }-> 0 :|: v0 >= 0, v1 >= 0, z = v0, z' = v1 Only complete derivations are relevant for the runtime complexity. ---------------------------------------- (11) CompleteCoflocoProof (FINISHED) Transformed the RNTS (where only complete derivations are relevant) into cost relations for CoFloCo: eq(start(V1, V, V9),0,[lt(V1, V, Out)],[V1 >= 0,V >= 0]). eq(start(V1, V, V9),0,[fac(V1, Out)],[V1 >= 0]). eq(start(V1, V, V9),0,[help(V1, V, Out)],[V1 >= 0,V >= 0]). eq(start(V1, V, V9),0,[if(V1, V, V9, Out)],[V1 >= 0,V >= 0,V9 >= 0]). eq(lt(V1, V, Out),1,[],[Out = 2,V = 1 + V2,V2 >= 0,V1 = 0]). eq(lt(V1, V, Out),1,[],[Out = 1,V3 >= 0,V1 = V3,V = 0]). eq(lt(V1, V, Out),1,[lt(V4, V5, Ret)],[Out = Ret,V = 1 + V5,V4 >= 0,V5 >= 0,V1 = 1 + V4]). eq(fac(V1, Out),1,[help(V6, 0, Ret1)],[Out = Ret1,V6 >= 0,V1 = V6]). eq(help(V1, V, Out),1,[lt(V8, V7, Ret0),if(Ret0, V7, V8, Ret2)],[Out = Ret2,V8 >= 0,V7 >= 0,V = V8,V1 = V7]). eq(if(V1, V, V9, Out),1,[help(V10, 1 + V11, Ret11)],[Out = 2 + Ret11 + V11,V1 = 2,V = V10,V11 >= 0,V10 >= 0,V9 = V11]). eq(if(V1, V, V9, Out),1,[],[Out = 1,V = V13,V12 >= 0,V1 = 1,V13 >= 0,V9 = V12]). eq(lt(V1, V, Out),0,[],[Out = 0,V15 >= 0,V14 >= 0,V1 = V15,V = V14]). eq(if(V1, V, V9, Out),0,[],[Out = 0,V17 >= 0,V9 = V18,V16 >= 0,V1 = V17,V = V16,V18 >= 0]). input_output_vars(lt(V1,V,Out),[V1,V],[Out]). input_output_vars(fac(V1,Out),[V1],[Out]). input_output_vars(help(V1,V,Out),[V1,V],[Out]). input_output_vars(if(V1,V,V9,Out),[V1,V,V9],[Out]). CoFloCo proof output: Preprocessing Cost Relations ===================================== #### Computed strongly connected components 0. recursive : [lt/3] 1. recursive : [help/3,if/4] 2. non_recursive : [fac/2] 3. non_recursive : [start/3] #### Obtained direct recursion through partial evaluation 0. SCC is partially evaluated into lt/3 1. SCC is partially evaluated into help/3 2. SCC is completely evaluated into other SCCs 3. SCC is partially evaluated into start/3 Control-Flow Refinement of Cost Relations ===================================== ### Specialization of cost equations lt/3 * CE 13 is refined into CE [14] * CE 11 is refined into CE [15] * CE 10 is refined into CE [16] * CE 12 is refined into CE [17] ### Cost equations --> "Loop" of lt/3 * CEs [17] --> Loop 10 * CEs [14] --> Loop 11 * CEs [15] --> Loop 12 * CEs [16] --> Loop 13 ### Ranking functions of CR lt(V1,V,Out) * RF of phase [10]: [V,V1] #### Partial ranking functions of CR lt(V1,V,Out) * Partial RF of phase [10]: - RF of loop [10:1]: V V1 ### Specialization of cost equations help/3 * CE 9 is refined into CE [18,19] * CE 8 is refined into CE [20,21] * CE 7 is refined into CE [22,23,24,25,26] ### Cost equations --> "Loop" of help/3 * CEs [21] --> Loop 14 * CEs [22] --> Loop 15 * CEs [20] --> Loop 16 * CEs [23,24,25,26] --> Loop 17 * CEs [19] --> Loop 18 * CEs [18] --> Loop 19 ### Ranking functions of CR help(V1,V,Out) * RF of phase [18]: [V1-V] #### Partial ranking functions of CR help(V1,V,Out) * Partial RF of phase [18]: - RF of loop [18:1]: V1-V ### Specialization of cost equations start/3 * CE 3 is refined into CE [27,28,29,30] * CE 1 is refined into CE [31] * CE 2 is refined into CE [32] * CE 4 is refined into CE [33,34,35,36,37] * CE 5 is refined into CE [38,39,40,41,42] * CE 6 is refined into CE [43,44,45,46,47,48,49] ### Cost equations --> "Loop" of start/3 * CEs [34,46,47] --> Loop 20 * CEs [27,28,29,30] --> Loop 21 * CEs [32,39,44] --> Loop 22 * CEs [31,33,35,36,37,38,40,41,42,43,45,48,49] --> Loop 23 ### Ranking functions of CR start(V1,V,V9) #### Partial ranking functions of CR start(V1,V,V9) Computing Bounds ===================================== #### Cost of chains of lt(V1,V,Out): * Chain [[10],13]: 1*it(10)+1 Such that:it(10) =< V1 with precondition: [Out=2,V1>=1,V>=V1+1] * Chain [[10],12]: 1*it(10)+1 Such that:it(10) =< V with precondition: [Out=1,V>=1,V1>=V] * Chain [[10],11]: 1*it(10)+0 Such that:it(10) =< V with precondition: [Out=0,V1>=1,V>=1] * Chain [13]: 1 with precondition: [V1=0,Out=2,V>=1] * Chain [12]: 1 with precondition: [V=0,Out=1,V1>=0] * Chain [11]: 0 with precondition: [Out=0,V1>=0,V>=0] #### Cost of chains of help(V1,V,Out): * Chain [[18],17]: 3*it(18)+3*s(2)+1*s(7)+2 Such that:it(18) =< V1-V aux(3) =< V1 s(2) =< aux(3) s(7) =< it(18)*aux(3) with precondition: [V>=1,V1>=V+1,Out>=V+2] * Chain [[18],14]: 3*it(18)+1*s(7)+1*s(8)+3 Such that:it(18) =< V1-V aux(4) =< V1 s(8) =< aux(4) s(7) =< it(18)*aux(4) with precondition: [V>=1,V1>=V+1,Out+3*V+1>=4*V1] * Chain [19,[18],17]: 6*it(18)+1*s(7)+5 Such that:aux(5) =< V1 it(18) =< aux(5) s(7) =< it(18)*aux(5) with precondition: [V=0,V1>=2,Out>=5] * Chain [19,[18],14]: 4*it(18)+1*s(7)+6 Such that:aux(6) =< V1 it(18) =< aux(6) s(7) =< it(18)*aux(6) with precondition: [V=0,V1>=2,Out+2>=4*V1] * Chain [19,17]: 2*s(2)+1*s(4)+5 Such that:s(4) =< 1 aux(1) =< V1 s(2) =< aux(1) with precondition: [V=0,Out=2,V1>=1] * Chain [19,14]: 1*s(8)+6 Such that:s(8) =< 1 with precondition: [V1=1,V=0,Out=3] * Chain [17]: 2*s(2)+1*s(4)+2 Such that:s(4) =< V aux(1) =< V1 s(2) =< aux(1) with precondition: [Out=0,V1>=0,V>=0] * Chain [16]: 3 with precondition: [V1=0,Out=1,V>=0] * Chain [15]: 2 with precondition: [V=0,Out=0,V1>=1] * Chain [14]: 1*s(8)+3 Such that:s(8) =< V1 with precondition: [Out=1,V1>=1,V>=V1] #### Cost of chains of start(V1,V,V9): * Chain [23]: 3*s(26)+22*s(28)+1*s(32)+2*s(37)+6*s(44)+2*s(46)+7 Such that:s(32) =< 1 s(43) =< V1-V aux(10) =< V1 aux(11) =< V s(28) =< aux(10) s(26) =< aux(11) s(37) =< s(28)*aux(10) s(44) =< s(43) s(46) =< s(44)*aux(10) with precondition: [V1>=0] * Chain [22]: 9 with precondition: [V1=1] * Chain [21]: 1*s(50)+7*s(51)+6*s(55)+2*s(57)+4 Such that:s(54) =< V-V9 s(50) =< V9+1 aux(13) =< V s(51) =< aux(13) s(55) =< s(54) s(57) =< s(55)*aux(13) with precondition: [V1=2,V>=0,V9>=0] * Chain [20]: 1*s(58)+12*s(60)+2*s(63)+6 Such that:s(58) =< 1 aux(14) =< V1 s(60) =< aux(14) s(63) =< s(60)*aux(14) with precondition: [V=0,V1>=0] Closed-form bounds of start(V1,V,V9): ------------------------------------- * Chain [23] with precondition: [V1>=0] - Upper bound: 22*V1+8+2*V1*V1+2*V1*nat(V1-V)+nat(V)*3+nat(V1-V)*6 - Complexity: n^2 * Chain [22] with precondition: [V1=1] - Upper bound: 9 - Complexity: constant * Chain [21] with precondition: [V1=2,V>=0,V9>=0] - Upper bound: 7*V+4+2*V*nat(V-V9)+(V9+1)+nat(V-V9)*6 - Complexity: n^2 * Chain [20] with precondition: [V=0,V1>=0] - Upper bound: 12*V1+7+2*V1*V1 - Complexity: n^2 ### Maximum cost of start(V1,V,V9): max([max([5,nat(V)*2*nat(V-V9)+nat(V)*7+nat(V9+1)+nat(V-V9)*6]),10*V1+1+2*V1*nat(V1-V)+nat(V)*3+nat(V1-V)*6+(12*V1+3+2*V1*V1)])+4 Asymptotic class: n^2 * Total analysis performed in 248 ms. ---------------------------------------- (12) BOUNDS(1, n^2) ---------------------------------------- (13) RenamingProof (BOTH BOUNDS(ID, ID)) Renamed function symbols to avoid clashes with predefined symbol. ---------------------------------------- (14) Obligation: The Runtime Complexity (full) of the given CpxTRS could be proven to be BOUNDS(n^1, INF). The TRS R consists of the following rules: lt(0', s(x)) -> true lt(x, 0') -> false lt(s(x), s(y)) -> lt(x, y) fac(x) -> help(x, 0') help(x, c) -> if(lt(c, x), x, c) if(true, x, c) -> times(s(c), help(x, s(c))) if(false, x, c) -> s(0') S is empty. Rewrite Strategy: FULL ---------------------------------------- (15) SlicingProof (LOWER BOUND(ID)) Sliced the following arguments: times/0 ---------------------------------------- (16) Obligation: The Runtime Complexity (full) of the given CpxTRS could be proven to be BOUNDS(n^1, INF). The TRS R consists of the following rules: lt(0', s(x)) -> true lt(x, 0') -> false lt(s(x), s(y)) -> lt(x, y) fac(x) -> help(x, 0') help(x, c) -> if(lt(c, x), x, c) if(true, x, c) -> times(help(x, s(c))) if(false, x, c) -> s(0') S is empty. Rewrite Strategy: FULL ---------------------------------------- (17) TypeInferenceProof (BOTH BOUNDS(ID, ID)) Infered types. ---------------------------------------- (18) Obligation: TRS: Rules: lt(0', s(x)) -> true lt(x, 0') -> false lt(s(x), s(y)) -> lt(x, y) fac(x) -> help(x, 0') help(x, c) -> if(lt(c, x), x, c) if(true, x, c) -> times(help(x, s(c))) if(false, x, c) -> s(0') Types: lt :: 0':s:times -> 0':s:times -> true:false 0' :: 0':s:times s :: 0':s:times -> 0':s:times true :: true:false false :: true:false fac :: 0':s:times -> 0':s:times help :: 0':s:times -> 0':s:times -> 0':s:times if :: true:false -> 0':s:times -> 0':s:times -> 0':s:times times :: 0':s:times -> 0':s:times hole_true:false1_0 :: true:false hole_0':s:times2_0 :: 0':s:times gen_0':s:times3_0 :: Nat -> 0':s:times ---------------------------------------- (19) OrderProof (LOWER BOUND(ID)) Heuristically decided to analyse the following defined symbols: lt, help They will be analysed ascendingly in the following order: lt < help ---------------------------------------- (20) Obligation: TRS: Rules: lt(0', s(x)) -> true lt(x, 0') -> false lt(s(x), s(y)) -> lt(x, y) fac(x) -> help(x, 0') help(x, c) -> if(lt(c, x), x, c) if(true, x, c) -> times(help(x, s(c))) if(false, x, c) -> s(0') Types: lt :: 0':s:times -> 0':s:times -> true:false 0' :: 0':s:times s :: 0':s:times -> 0':s:times true :: true:false false :: true:false fac :: 0':s:times -> 0':s:times help :: 0':s:times -> 0':s:times -> 0':s:times if :: true:false -> 0':s:times -> 0':s:times -> 0':s:times times :: 0':s:times -> 0':s:times hole_true:false1_0 :: true:false hole_0':s:times2_0 :: 0':s:times gen_0':s:times3_0 :: Nat -> 0':s:times Generator Equations: gen_0':s:times3_0(0) <=> 0' gen_0':s:times3_0(+(x, 1)) <=> s(gen_0':s:times3_0(x)) The following defined symbols remain to be analysed: lt, help They will be analysed ascendingly in the following order: lt < help ---------------------------------------- (21) RewriteLemmaProof (LOWER BOUND(ID)) Proved the following rewrite lemma: lt(gen_0':s:times3_0(n5_0), gen_0':s:times3_0(+(1, n5_0))) -> true, rt in Omega(1 + n5_0) Induction Base: lt(gen_0':s:times3_0(0), gen_0':s:times3_0(+(1, 0))) ->_R^Omega(1) true Induction Step: lt(gen_0':s:times3_0(+(n5_0, 1)), gen_0':s:times3_0(+(1, +(n5_0, 1)))) ->_R^Omega(1) lt(gen_0':s:times3_0(n5_0), gen_0':s:times3_0(+(1, n5_0))) ->_IH true We have rt in Omega(n^1) and sz in O(n). Thus, we have irc_R in Omega(n). ---------------------------------------- (22) Complex Obligation (BEST) ---------------------------------------- (23) Obligation: Proved the lower bound n^1 for the following obligation: TRS: Rules: lt(0', s(x)) -> true lt(x, 0') -> false lt(s(x), s(y)) -> lt(x, y) fac(x) -> help(x, 0') help(x, c) -> if(lt(c, x), x, c) if(true, x, c) -> times(help(x, s(c))) if(false, x, c) -> s(0') Types: lt :: 0':s:times -> 0':s:times -> true:false 0' :: 0':s:times s :: 0':s:times -> 0':s:times true :: true:false false :: true:false fac :: 0':s:times -> 0':s:times help :: 0':s:times -> 0':s:times -> 0':s:times if :: true:false -> 0':s:times -> 0':s:times -> 0':s:times times :: 0':s:times -> 0':s:times hole_true:false1_0 :: true:false hole_0':s:times2_0 :: 0':s:times gen_0':s:times3_0 :: Nat -> 0':s:times Generator Equations: gen_0':s:times3_0(0) <=> 0' gen_0':s:times3_0(+(x, 1)) <=> s(gen_0':s:times3_0(x)) The following defined symbols remain to be analysed: lt, help They will be analysed ascendingly in the following order: lt < help ---------------------------------------- (24) LowerBoundPropagationProof (FINISHED) Propagated lower bound. ---------------------------------------- (25) BOUNDS(n^1, INF) ---------------------------------------- (26) Obligation: TRS: Rules: lt(0', s(x)) -> true lt(x, 0') -> false lt(s(x), s(y)) -> lt(x, y) fac(x) -> help(x, 0') help(x, c) -> if(lt(c, x), x, c) if(true, x, c) -> times(help(x, s(c))) if(false, x, c) -> s(0') Types: lt :: 0':s:times -> 0':s:times -> true:false 0' :: 0':s:times s :: 0':s:times -> 0':s:times true :: true:false false :: true:false fac :: 0':s:times -> 0':s:times help :: 0':s:times -> 0':s:times -> 0':s:times if :: true:false -> 0':s:times -> 0':s:times -> 0':s:times times :: 0':s:times -> 0':s:times hole_true:false1_0 :: true:false hole_0':s:times2_0 :: 0':s:times gen_0':s:times3_0 :: Nat -> 0':s:times Lemmas: lt(gen_0':s:times3_0(n5_0), gen_0':s:times3_0(+(1, n5_0))) -> true, rt in Omega(1 + n5_0) Generator Equations: gen_0':s:times3_0(0) <=> 0' gen_0':s:times3_0(+(x, 1)) <=> s(gen_0':s:times3_0(x)) The following defined symbols remain to be analysed: help