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<!DOCTYPE PROOF SYSTEM "http://a3pat.ensiie.fr/pub/a3pat.dtd">
<PROOF><SIGNATURE><SYMBOLLIST><SYMBOL arity="0" unmarked=""><NAME>b</NAME></SYMBOL><SYMBOL arity="2" unmarked="g"><NAME>Marked_g</NAME></SYMBOL><SYMBOL arity="0" unmarked=""><NAME>a</NAME></SYMBOL><SYMBOL arity="2" unmarked=""><NAME>f</NAME></SYMBOL><SYMBOL arity="2" unmarked="f"><NAME>Marked_f</NAME></SYMBOL><SYMBOL arity="2" unmarked=""><NAME>g</NAME></SYMBOL></SYMBOLLIST><VARLIST><VAR>z</VAR><VAR>y</VAR><VAR>x</VAR></VARLIST></SIGNATURE><PROPERTY criterion="dp" prop="sntrs"><SYSTEM><REWSYS><RULE><LHS>f(a,x)</LHS><RHS>g(a,x)</RHS></RULE><RULE><LHS>g(a,x)</LHS><RHS>f(b,x)</RHS></RULE><RULE><LHS>f(a,x)</LHS><RHS>f(b,x)</RHS></RULE></REWSYS></SYSTEM><CRITERION/><PROPERTY criterion="weakgraph" prop="sndp"><SYSTEM><DPSYS><REWSYS><RULE><LHS>f(a,x)</LHS><RHS>g(a,x)</RHS></RULE><RULE><LHS>g(a,x)</LHS><RHS>f(b,x)</RHS></RULE><RULE><LHS>f(a,x)</LHS><RHS>f(b,x)</RHS></RULE></REWSYS><DPLIST><DPRULE num="0"><LHS>Marked_f(a,x)</LHS><RHS>Marked_g(a,x)</RHS></DPRULE><DPRULE num="1"><LHS>Marked_g(a,x)</LHS><RHS>Marked_f(b,x)</RHS></DPRULE><DPRULE num="2"><LHS>Marked_f(a,x)</LHS><RHS>Marked_f(b,x)</RHS></DPRULE></DPLIST></DPSYS></SYSTEM><CRITERION><DAG approx="simpl"><CCLIST><NONSCC num="0"><NODE ref="2"/></NONSCC><NONSCC num="1"><NODE ref="1"/></NONSCC><NONSCC num="2"><NODE ref="0"/></NONSCC></CCLIST><EDGE end="1" start="2"/></DAG></CRITERION></PROPERTY></PROPERTY></PROOF>
