Running examples in 'Diderot-Ex.R' failed
The error most likely occurred in:

> ### Name: compute_BC_ranking
> ### Title: Function to compute the Betweenness Centrality ranking.
> ### Aliases: compute_BC_ranking 'Betweenness Centrality'
> 
> ### ** Examples
> 
> ## Don't show: 
> # Generate corpora
> corp1<-data.frame(Authors=paste("Author",round(runif(45,1,20)),sep=""),Title=paste("Title",seq(1,45), sep=""), Year=round(runif(45,1990,2018)), References=NA,stringsAsFactors=FALSE)
> corp2<-data.frame(Authors=paste("Author",round(runif(65,15,35)),sep=""),Title=paste("Title",seq(46,110), sep=""), Year=round(runif(65,1990,2018)), References=NA, stringsAsFactors=FALSE)
> 
> len1<-length(corp1$Authors)
> len2<-length(corp2$Authors)
> lnall<-len1+len2
> 
> for (i in seq(1:lnall)) {
+   str<-""
+   for (j in seq(1:round(runif(1,1,4)))) {
+     rn<-round(runif(1,1,lnall))
+     if (rn > len1) { 
+       str<-sprintf("%s %s. %d. %s;", str, corp2$Authors[rn-len1], corp2$Year[rn-len1], corp2$Title[rn-len1])
+     } else {
+       str<-sprintf("%s %s. %d. %s;", str, corp1$Authors[rn], corp1$Year[rn], corp1$Title[rn])
+     }
+   }
+   if (i>len1) {
+     corp2$References[i-len1]<-str
+   } else corp1$References[i]<-str
+ }
> 
> # Create joint references
> for (i in seq(1:5)) {
+   corp1<-rbind(corp1, corp2[runif(1,1,len2),])
+   corp2<-rbind(corp2, corp1[runif(1,1,len1),])
+ }
> 
> # Add duplicate entry
> corp1<-rbind(corp1, corp1[1,])
> 
> tempfi1<-file.path(tempdir(),"corpus1.csv")
> tempfi2<-file.path(tempdir(),"corpus2.csv")
> write.csv(corp1, tempfi1)
> write.csv(corp2, tempfi2)
> ## End(Don't show)
> 
> labels<-c("Corpus1","Corpus2")
> 
> # Build a bibliographical dataset from Scopus exports
> db<-create_bibliography(corpora_files=c(tempfi1,tempfi2), 
+                         labels=labels, keywords=NA)
[1] "File D:\\temp\\RtmpAbRzVm/corpus1.csv contains 51 records"
[1] "File D:\\temp\\RtmpAbRzVm/corpus2.csv contains 70 records"
> ## Don't show: 
> unlink(c(tempfi1, tempfi2))
> ## End(Don't show)
> 
> # Build graph
> gr<-build_graph(db=db,small.year.mismatch=TRUE, attrs=c("Corpus","Year","Authors"), nb.cores=1)
Error in makePSOCKcluster(names = spec, ...) : 
  Cluster setup failed. 1 worker of 1 failed to connect.
Calls: build_graph -> <Anonymous> -> makePSOCKcluster
Execution halted