His invariant had been missed completely by topologists, in spite of intense activity in closely related areas during the preceding 60 years, and it was a complete surprise.
Kanyang invariant had ay hindi nakuha sa pamamagitan ng ganap na topologists, kahit na mahimbing na aktibidad sa mga lugar na may malapit na kaugnayan sa panahon ng 60 taon na nakalipas, at ito ay isang kumpletong sorpresa.