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Higher Order Rewriting Union Beta pair #487093757
details
property
value
status
complete
benchmark
h17.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
Hamana_Kikuchi_18
run statistics
property
value
solver
Wanda 2.2a
configuration
default
runtime (wallclock)
0.275721 seconds
cpu usage
0.274122
user time
0.240232
system time
0.03389
max virtual memory
113188.0
max residence set size
9656.0
stage attributes
key
value
starexec-result
YES
output
YES We consider the system theBenchmark. Alphabet: cons : [] --> a -> alist -> alist map : [] --> (a -> a) -> alist -> alist nil : [] --> alist o : [] --> (a -> a) -> (a -> a) -> a -> a Rules: map (/\x.f x) nil => nil map (/\x.f x) (cons y z) => cons (f y) (map (/\u.f u) z) map (/\x.f x) (map (/\y.g y) z) => map (/\u.o (/\v.f v) (/\w.g w) u) z o (/\x.f x) (/\y.g y) z => f (g z) Using the transformations described in [Kop11], this system can be brought in a form without leading free variables in the left-hand side, and where the left-hand side of a variable is always a functional term or application headed by a functional term. We now transform the resulting AFS into an AFSM by replacing all free variables by meta-variables (with arity 0). This leads to the following AFSM: Alphabet: cons : [a * alist] --> alist map : [a -> a * alist] --> alist nil : [] --> alist o : [a -> a * a -> a * a] --> a ~AP1 : [a -> a * a] --> a Rules: map(/\x.~AP1(F, x), nil) => nil map(/\x.~AP1(F, x), cons(X, Y)) => cons(~AP1(F, X), map(/\y.~AP1(F, y), Y)) map(/\x.~AP1(F, x), map(/\y.~AP1(G, y), X)) => map(/\z.o(/\u.~AP1(F, u), /\v.~AP1(G, v), z), X) o(/\x.~AP1(F, x), /\y.~AP1(G, y), X) => ~AP1(F, ~AP1(G, X)) map(/\x.o(F, G, x), nil) => nil map(/\x.o(F, G, x), cons(X, Y)) => cons(o(F, G, X), map(/\y.o(F, G, y), Y)) map(/\x.o(F, G, x), map(/\y.~AP1(H, y), X)) => map(/\z.o(/\u.o(F, G, u), /\v.~AP1(H, v), z), X) map(/\x.~AP1(F, x), map(/\y.o(G, H, y), X)) => map(/\z.o(/\u.~AP1(F, u), /\v.o(G, H, v), z), X) o(/\x.o(F, G, x), /\y.~AP1(H, y), X) => o(F, G, ~AP1(H, X)) o(/\x.~AP1(F, x), /\y.o(G, H, y), X) => ~AP1(F, o(G, H, X)) map(/\x.o(F, G, x), map(/\y.o(H, I, y), X)) => map(/\z.o(/\u.o(F, G, u), /\v.o(H, I, v), z), X) o(/\x.o(F, G, x), /\y.o(H, I, y), X) => o(F, G, o(H, I, X)) ~AP1(F, X) => F X Symbol ~AP1 is an encoding for application that is only used in innocuous ways. We can simplify the program (without losing non-termination) by removing it. Additionally, we can remove some (now-)redundant rules. This gives: Alphabet: cons : [a * alist] --> alist map : [a -> a * alist] --> alist nil : [] --> alist o : [a -> a * a -> a * a] --> a Rules: map(/\x.X(x), nil) => nil map(/\x.X(x), cons(Y, Z)) => cons(X(Y), map(/\y.X(y), Z)) map(/\x.X(x), map(/\y.Y(y), Z)) => map(/\z.o(/\u.X(u), /\v.Y(v), z), Z) o(/\x.X(x), /\y.Y(y), Z) => X(Y(Z)) We use the dependency pair framework as described in [Kop12, Ch. 6/7], with static dependency pairs (see [KusIsoSakBla09] and the adaptation for AFSMs and accessible arguments in [FuhKop19]). We thus obtain the following dependency pair problem (P_0, R_0, computable, formative): Dependency Pairs P_0: 0] map#(/\x.X(x), cons(Y, Z)) =#> map#(/\y.X(y), Z) 1] map#(/\x.X(x), map(/\y.Y(y), Z)) =#> map#(/\z.o(/\u.X(u), /\v.Y(v), z), Z) 2] map#(/\x.X(x), map(/\y.Y(y), Z)) =#> o#(/\z.X(z), /\u.Y(u), U) Rules R_0: map(/\x.X(x), nil) => nil map(/\x.X(x), cons(Y, Z)) => cons(X(Y), map(/\y.X(y), Z)) map(/\x.X(x), map(/\y.Y(y), Z)) => map(/\z.o(/\u.X(u), /\v.Y(v), z), Z) o(/\x.X(x), /\y.Y(y), Z) => X(Y(Z)) Thus, the original system is terminating if (P_0, R_0, computable, formative) is finite. We consider the dependency pair problem (P_0, R_0, computable, 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 : 0, 1, 2 * 2 : This graph has the following strongly connected components: P_1: map#(/\x.X(x), cons(Y, Z)) =#> map#(/\y.X(y), Z) map#(/\x.X(x), map(/\y.Y(y), Z)) =#> map#(/\z.o(/\u.X(u), /\v.Y(v), z), Z) 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). Thus, the original system is terminating if (P_1, R_0, computable, formative) is finite. We consider the dependency pair problem (P_1, R_0, computable, formative).
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