在研究@瓦尔建议后。我把这些拼凑起来。我不知道这是不是很正确，但保存在这里，以防有人发现作为一个有用的起点。

private static Analyzer GetGreekSymbolAgnosticAnalyzer()
    {
        NormalizeCharMap.Builder builder = new NormalizeCharMap.Builder();
        builder.Add("α", "alpha");
        builder.Add("β", "beta");
        builder.Add("ω", "omega");

        NormalizeCharMap norm = builder.Build();
        Analyzer analyzer = Analyzer.NewAnonymous(createComponents: (fieldName, reader) =>
        {
            Tokenizer tokenizer = new StandardTokenizer(LuceneVersion.LUCENE_48, reader);
            return new TokenStreamComponents(tokenizer, new StandardFilter(LuceneVersion.LUCENE_48, tokenizer));
        }, initReader: (fieldName, reader) => new MappingCharFilter(norm, reader));

        return analyzer;
    }