YES
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<certificationProblem xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="cpf.xsd"><input><trsInput><trs><rules><rule><lhs><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></lhs><rhs><funapp><name>f</name><arg><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></arg></funapp></rhs></rule><rule><lhs><funapp><name>a</name></funapp></lhs><rhs><funapp><name>b</name></funapp></rhs></rule><rule><lhs><funapp><name>f</name><arg><var>x</var></arg></funapp></lhs><rhs><funapp><name>f</name><arg><funapp><name>b</name></funapp></arg></funapp></rhs></rule></rules></trs></trsInput></input><cpfVersion>2.1</cpfVersion><proof><crProof><compositionalPcps><trsC><rules><rule><lhs><funapp><name>f</name><arg><var>x</var></arg></funapp></lhs><rhs><funapp><name>f</name><arg><funapp><name>b</name></funapp></arg></funapp></rhs></rule></rules></trsC><trsP><rules /></trsP><joinSequences><critPairInfo><left><funapp><name>f</name><arg><funapp><name>b</name></funapp></arg></funapp></left><peak><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></peak><right><funapp><name>f</name><arg><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></arg></funapp></right><overlapPositions><positionInTerm /></overlapPositions><intermediateTerms /></critPairInfo><critPairInfo><left><funapp><name>f</name><arg><funapp><name>b</name></funapp></arg></funapp></left><peak><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></peak><right><funapp><name>f</name><arg><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></arg></funapp></right><overlapPositions><positionInTerm><position>1</position></positionInTerm></overlapPositions><intermediateTerms /></critPairInfo><critPairInfo><left><funapp><name>f</name><arg><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></arg></funapp></left><peak><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></peak><right><funapp><name>f</name><arg><funapp><name>b</name></funapp></arg></funapp></right><overlapPositions><positionInTerm /></overlapPositions><intermediateTerms /></critPairInfo></joinSequences><joinSequences><critPairInfo><left><funapp><name>f</name><arg><funapp><name>b</name></funapp></arg></funapp></left><peak><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></peak><right><funapp><name>f</name><arg><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></arg></funapp></right><overlapPositions><positionInTerm /></overlapPositions><intermediateTerms /></critPairInfo><critPairInfo><left><funapp><name>f</name><arg><funapp><name>b</name></funapp></arg></funapp></left><peak><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></peak><right><funapp><name>f</name><arg><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></arg></funapp></right><overlapPositions><positionInTerm><position>1</position></positionInTerm></overlapPositions><intermediateTerms /></critPairInfo><critPairInfo><left><funapp><name>f</name><arg><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></arg></funapp></left><peak><funapp><name>f</name><arg><funapp><name>a</name></funapp></arg></funapp></peak><right><funapp><name>f</name><arg><funapp><name>b</name></funapp></arg></funapp></right><overlapPositions><positionInTerm /></overlapPositions><intermediateTerms /></critPairInfo></joinSequences><relativeTerminationProof><rIsEmpty /></relativeTerminationProof><crProof><compositionalPcps><trsC><rules /></trsC><trsP><rules /></trsP><joinSequences /><joinSequences /><relativeTerminationProof><rIsEmpty /></relativeTerminationProof><crProof><orthogonal /></crProof></compositionalPcps></crProof></compositionalPcps></crProof></proof><origin><proofOrigin><tool><name>Hakusan</name><version>0.10</version></tool></proofOrigin></origin></certificationProblem>