Compose two structured cospans along a shared foot

Given M: A -> X <- B and N: B -> Y <- C (where B is the shared foot), compute the composite M;N: A -> Z <- C via pushout of X and Y over B.

Usage

compose_cospans(M, N)

Arguments

M

StructuredCospan with at least 2 legs (left=first, right=last)

N

StructuredCospan with at least 2 legs (left=first, right=last)

Value

StructuredCospan with 2 legs: left from M, right from N

Examples

# Compose two path-graph cospans end-to-end
g1 <- path_graph(3)
sc1 <- open_acset(g1, "V", 1L, 3L)
g2 <- path_graph(2)
sc2 <- open_acset(g2, "V", 1L, 2L)
composed <- compose_cospans(sc1, sc2)
nv(cospan_apex(composed)) # 4 (shared vertex merged)
#> [1] 4