A binary cover with a contractible second piece: local context

Project map · Chapter map · Full theorem DAG · Open textbook statement

This local map shows one dependency hop in either direction. The highlighted item is the current focus. What the colours mean

fully proved4Proved, and every prerequisite is fully proved too.

graph LR n0("Retractions and deformation retracts on the fundamental group"):::fully_proved n1["Binary van Kampen is a group pushout"]:::fully_proved n2["A binary cover with a contractible second piece"]:::fully_proved n3["Attaching higher cells preserves the fundamental group"]:::fully_proved n0 -.-> n2 n1 -.-> n2 n2 -.-> n3 click n0 "../../../../../roadmap/fundamental-group/basic-constructions/index.html#retractions-fundamental-group" "Retractions and deformation retracts on the fundamental group — 1 item · 1 fully proved" click n1 "../../../../../roadmap/fundamental-group/van-kampen/index.html#binary-van-kampen-pushout" "Binary van Kampen is a group pushout — 1 item · 1 fully proved" class n2 focus click n2 "../../../../../roadmap/fundamental-group/van-kampen/cell-attachment-support/index.html#binary-cover-contractible-piece" "A binary cover with a contractible second piece — 1 item · 1 fully proved" click n3 "../../../../../roadmap/fundamental-group/van-kampen/index.html#attach-higher-cells-fundamental-group" "Attaching higher cells preserves the fundamental group — 1 item · 1 fully proved"