Collapsing the boundary of a one-disk gives the circle: 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("A single cone attachment has a two-set open cover"):::fully_proved n1["The cone on a disk boundary is the disk"]:::fully_proved n2["Collapsing the boundary of a one-disk gives the circle"]:::fully_proved n3["A wedge of circles is an indexed one-cell attachment"]:::fully_proved n1 --> n2 n0 --> n1 n0 --> n2 n2 --> n3 click n0 "../../../../../roadmap/fundamental-group/van-kampen/cell-attachment-support/index.html#single-cone-open-cover" "A single cone attachment has a two-set open cover — 1 item · 1 fully proved" click n1 "../../../../../roadmap/fundamental-group/van-kampen/cell-attachment-support/index.html#cone-disk-homeomorphism" "The cone on a disk boundary is the disk — 1 item · 1 fully proved" class n2 focus click n2 "../../../../../roadmap/fundamental-group/van-kampen/presentation-complex/index.html#circle-one-cell-quotient" "Collapsing the boundary of a one-disk gives the circle — 1 item · 1 fully proved" click n3 "../../../../../roadmap/fundamental-group/van-kampen/presentation-complex/index.html#wedge-circles-one-skeleton" "A wedge of circles is an indexed one-cell attachment — 1 item · 1 fully proved"