% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/structure.info.R
\name{are_adjacent}
\alias{are_adjacent}
\title{Are two vertices adjacent?}
\usage{
are_adjacent(graph, v1, v2)
}
\arguments{
\item{graph}{The graph.}

\item{v1}{The first vertex, tail in directed graphs.}

\item{v2}{The second vertex, head in directed graphs.}
}
\value{
A logical scalar, \code{TRUE} if edge \verb{(v1, v2)} exists in the graph.
}
\description{
The order of the vertices only matters in directed graphs,
where the existence of a directed \verb{(v1, v2)} edge is queried.
}
\section{Related documentation in the C library}{
\href{https://igraph.org/c/html/0.10.17/igraph-Structural.html#igraph_are_adjacent}{\code{are_adjacent()}}, \href{https://igraph.org/c/html/0.10.17/igraph-Basic.html#igraph_vcount}{\code{vcount()}}
}

\examples{
ug <- make_ring(10)
ug
are_adjacent(ug, 1, 2)
are_adjacent(ug, 2, 1)

dg <- make_ring(10, directed = TRUE)
dg
are_adjacent(ug, 1, 2)
are_adjacent(ug, 2, 1)
}
\seealso{
Other structural queries: 
\code{\link{[.igraph}()},
\code{\link{[[.igraph}()},
\code{\link{adjacent_vertices}()},
\code{\link{ends}()},
\code{\link{get_edge_ids}()},
\code{\link{gorder}()},
\code{\link{gsize}()},
\code{\link{head_of}()},
\code{\link{incident}()},
\code{\link{incident_edges}()},
\code{\link{is_directed}()},
\code{\link{neighbors}()},
\code{\link{tail_of}()}
}
\concept{structural queries}
