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Higher Order Rewriting Union Beta pair #487093871
details
property
value
status
complete
benchmark
findzero.xml
ran by
Akihisa Yamada
cpu timeout
1200 seconds
wallclock timeout
300 seconds
memory limit
137438953472 bytes
execution host
n140.star.cs.uiowa.edu
space
Mixed_HO_10
run statistics
property
value
solver
Wanda 2.2a
configuration
default
runtime (wallclock)
0.992763 seconds
cpu usage
0.99033
user time
0.900462
system time
0.089868
max virtual memory
138588.0
max residence set size
24304.0
stage attributes
key
value
starexec-result
YES
output
YES We consider the system theBenchmark. Alphabet: 0 : [] --> nat find0 : [nat -> nat * nat * nat] --> nat if : [nat * nat * nat] --> nat min : [nat * nat] --> nat nul : [nat -> nat * nat] --> nat s : [nat] --> nat Rules: min(s(x), s(y)) => min(x, y) min(x, 0) => 0 min(0, x) => 0 min(nul(f, x), y) => nul(f, min(x, y)) nul(f, x) => find0(f, 0, x) find0(f, x, 0) => x find0(f, x, s(y)) => if(f x, find0(f, s(x), y), x) if(s(x), y, z) => y if(0, x, y) => y This AFS is converted to an AFSM simply by replacing all free variables by meta-variables (with arity 0). We observe that the rules contain a first-order subset: if(s(X), Y, Z) => Y if(0, X, Y) => Y Moreover, the system is finitely branching. Thus, by [Kop12, Thm. 7.55], we may omit all first-order dependency pairs from the dependency pair problem (DP(R), R) if this first-order part is Ce-terminating when seen as a many-sorted first-order TRS. According to the external first-order termination prover, this system is indeed Ce-terminating: || Input TRS: || 1: if(s(PeRCenTX),PeRCenTY,PeRCenTZ) -> PeRCenTY || 2: if(0(),PeRCenTX,PeRCenTY) -> PeRCenTY || 3: TIlDePAIR(PeRCenTX,PeRCenTY) -> PeRCenTX || 4: TIlDePAIR(PeRCenTX,PeRCenTY) -> PeRCenTY || Number of strict rules: 4 || Direct POLO(bPol) ... removes: 4 1 3 2 || TIlDePAIR w: x1 + 2 * x2 + 1 || s w: x1 + 1 || if w: 2 * x1 + 2 * x2 + 2 * x3 || 0 w: 1 || Number of strict rules: 0 || We use the dependency pair framework as described in [Kop12, Ch. 6/7], with dynamic dependency pairs. After applying [Kop12, Thm. 7.22] to denote collapsing dependency pairs in an extended form, we thus obtain the following dependency pair problem (P_0, R_0, minimal, formative): Dependency Pairs P_0: 0] min#(s(X), s(Y)) =#> min#(X, Y) 1] min#(nul(F, X), Y) =#> nul#(F, min(X, Y)) 2] min#(nul(F, X), Y) =#> min#(X, Y) 3] nul#(F, X) =#> find0#(F, 0, X) 4] find0#(F, X, s(Y)) =#> if#(F X, find0(F, s(X), Y), X) 5] find0#(F, X, s(Y)) =#> F(X) 6] find0#(F, X, s(Y)) =#> find0#(F, s(X), Y) Rules R_0: min(s(X), s(Y)) => min(X, Y) min(X, 0) => 0 min(0, X) => 0 min(nul(F, X), Y) => nul(F, min(X, Y)) nul(F, X) => find0(F, 0, X) find0(F, X, 0) => X find0(F, X, s(Y)) => if(F X, find0(F, s(X), Y), X) if(s(X), Y, Z) => Y if(0, X, Y) => Y Thus, the original system is terminating if (P_0, R_0, minimal, formative) is finite. We consider the dependency pair problem (P_0, R_0, minimal, formative). We place the elements of P in a dependency graph approximation G (see e.g. [Kop12, Thm. 7.27, 7.29], as follows: * 0 : 0, 1, 2 * 1 : 3 * 2 : 0, 1, 2 * 3 : 4, 5, 6 * 4 : * 5 : 0, 1, 2, 3, 4, 5, 6 * 6 : 4, 5, 6 This graph has the following strongly connected components: P_1: min#(s(X), s(Y)) =#> min#(X, Y) min#(nul(F, X), Y) =#> nul#(F, min(X, Y)) min#(nul(F, X), Y) =#> min#(X, Y) nul#(F, X) =#> find0#(F, 0, X) find0#(F, X, s(Y)) =#> F(X) find0#(F, X, s(Y)) =#> find0#(F, s(X), Y) By [Kop12, Thm. 7.31], we may replace any dependency pair problem (P_0, R_0, m, f) by (P_1, R_0, m, f).
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