[R] Information Frequency problem calculation

[jarod_v6 at libero.it]

Dear All,

I Have a dataframe like that:

Name1 Name2 category

mauro francesco E234
luca   giuseppe  E5578
luca   franco  E5569
maria luca E4556
...
I would like to calculate the frequency of many time in my data I found  in 
the list name:

a<-read.table("pippo.csv",header=T,sep="\t")
name1<-as.character(a[,1])
name2<-as.character(a[,2])
category<-as.character(a[,3])

for(i in 1:lenght(name1)){
 re <-which(name1 == name2)

}

So how can create a table of frequncy of many times I found a name in column 
one respect to the second ?
Thanks in advance for your help!
M.