CREATE TABLE table_31598 ("Schemas" TEXT, "Flexible" TEXT, "Semantic verification" TEXT, "Dictionary" TEXT, "Information Model" TEXT, "Synonyms and homonyms" TEXT, "Dialecting" TEXT, "Web standard" TEXT, "Transformations" TEXT, "Lightweight" TEXT, "Human readable" TEXT)

What is the lightweight value with no information model and the flexible value is unknown?
SELECT "Lightweight" FROM table_31598 WHERE "Information Model" = 'no' AND "Flexible" = 'unknown'
SELECT "Lightweight" FROM "table_31598" WHERE "Flexible" = 'unknown' AND "Information Model" = 'no'