shortdata <- data.frame(X=c(5,4,1,2),Y=c(10,8,1,3),Z=c('A','A','B','B'))

attach(shortdata)

# 2/

plot(X,Y,col=Z,xlab='X',ylab='Y',lwd=2)

points(x=4,y=6,'p',col='blue',lwd=2)

text(x=4.2,y=6,labels=c('?'),col='blue',cex=1,lwd=2)

scan('')

# 3/

dlogrule <- glm(Z~X+Y,data=shortdata,family=binomial(lin='logit'))

print(summary(dlogrule))

# 4/ 

print(predict(dlogrule,new=data.frame(X=4,Y=6)))

# 4/ 

plot(X,Y,col=Z,xlab='X',ylab='Y',lwd=2)

abline(-dlogrule$coefficients[[1]]/dlogrule$coefficients[[3]],-dlogrule$coefficients[[2]]/dlogrule$coefficients[[3]],col='red')

points(4,6,col='red',lwd=2)