Dynamic Enumeration Tree

r1r2r3r4 { }

r1r2r3 {c}

ab {}

a{r2}

r1r2 {ac}

ac { r2}

r1r2r4 { }

r1 {abc}

r1 {abc}

r1r3 {bc}

r1r3r4 { }

b{r3}

bc {r3 }

r1r4 { }

ac{r1 }

acd { }

a{r1}

ad{ }

{ }

r2 {acd}

c {r1r3}

cd { }

ac: {r1r2} bc: {r1r3} c: {r1r2r3}

d {r4 }

r3 {bc}

bc {r1 }

b{r1 }

c{r1r2 }

r4  {d}

Row enumeration to Feature Enumeration