HLG cannot be determinized after converting to openfst format

[wangtiance]

I generated HLG following the procedures in https://github.com/k2-fsa/icefall/blob/master/egs/librispeech/ASR/local/compile_hlg_using_openfst.py

Now, since k2 does not support minimization, I tried converting the resulting HLG to fst format and do det and min.

HLG_fst = kaldifst.utils.k2_to_openfst(HLG, olabels='aux_labels') kaldifst.determinize_star(HLG_fst)

But I get the error:

• RuntimeError: /project/kaldifst/csrc/determinize-star-inl.h:void fst::DeterminizerStar::ProcessTransition(fst::DeterminizerStar::OutputStateId, fst::DeterminizerStar::Label, std::vector<fst::DeterminizerStar::Element>*) [with F = fst::VectorFst<fst::ArcTpl<fst::TropicalWeightTpl > >; fst::DeterminizerStar::OutputStateId = int; fst::DeterminizerStar::Label = int]:966 [E] FST was not functional -> not determinizable

However, based on the definition here, I don't see why HLG is not functional. Could someone help? Thanks! https://www.openfst.org/twiki/bin/view/FST/FstGlossary#FunctionalDef