Columbia subject headings:
Algebra.
Homotopy theory--Congresses.
Perturbation (Mathematics)--Congresses.
Harvard subject headings:
Algebra.
Homotopy theory--Congresses.
Perturbation (Mathematics)--Congresses.
Princeton subject headings:
Algebra.
Homotopy theory--Congresses.
Perturbation (Mathematics)--Congresses.