// supersetOf reports whether y ⊆ xl.
func (xl termlist) supersetOf(y *term) bool {
	for _, x := range xl {
		if y.subsetOf(x) {
			return true
		}
	}
	return false
}

// subsetOf reports whether xl ⊆ yl.
func (xl termlist) subsetOf(yl termlist) bool {
	if yl.isEmpty() {
		return xl.isEmpty()
	}

	// each term x of xl must be a subset of yl
	for _, x := range xl {
		if !yl.supersetOf(x) {

// supersetOf reports whether y ⊆ xl.
func (xl termlist) supersetOf(y *term) bool {
	for _, x := range xl {
		if y.subsetOf(x) {
			return true
		}
	}
	return false
}

// subsetOf reports whether xl ⊆ yl.
func (xl termlist) subsetOf(yl termlist) bool {
	if yl.isEmpty() {
		return xl.isEmpty()
	}

	// each term x of xl must be a subset of yl
	for _, x := range xl {
		if !yl.supersetOf(x) {

// supersetOf reports whether y ⊆ xl.
func (xl termlist) supersetOf(y *term) bool {
	for _, x := range xl {
		if y.subsetOf(x) {
			return true
		}
	}
	return false
}

// subsetOf reports whether xl ⊆ yl.
func (xl termlist) subsetOf(yl termlist) bool {
	if yl.isEmpty() {
		return xl.isEmpty()
	}

	// each term x of xl must be a subset of yl
	for _, x := range xl {
		if !yl.supersetOf(x) {

			right:    labels.Instance{"foo": ""},
			expected: result{false, false},
		},
	}
	for _, c := range cases {
		var got result
		got.subsetOf = c.left.SubsetOf(c.right)
		got.selected = c.left.Match(c.right)
		if got != c.expected {
			t.Errorf("%v.SubsetOf(%v) got %v, expected %v", c.left, c.right, got, c.expected)
		}
	}
}

func TestString(t *testing.T) {
	cases := []struct {
		input    labels.Instance

// could have labels gitCommit=aeiou234, region=us-east, while v2 instances could
// have labels name=kittyCat,region=us-east.
type Instance map[string]string

// SubsetOf is true if the label has same values for the keys
func (i Instance) SubsetOf(that Instance) bool {
	if len(i) == 0 {
		return true
	}

	if len(that) == 0 || len(that) < len(i) {
		return false
	}

	for k, v1 := range i {

	}

	// both are non-wildcards, so do normal string comparison
	return n == o
}

// SubsetOf returns true if this hostname is a valid subset of the other hostname. The semantics are
// the same as "Matches", but only in one direction (i.e., n is covered by o).
func (n Name) SubsetOf(o Name) bool {
	hWildcard := n.IsWildCarded()
	oWildcard := o.IsWildCarded()

	if hWildcard {
		if oWildcard {

		{"int | ~string", "string | int | ∅ | string", false},
		{"int | myInt", "string | ~int | ∅ | string", true},
	} {
		xl := maketl(test.xl)
		yl := maketl(test.yl)
		got := xl.subsetOf(yl)
		if got != test.want {
			t.Errorf("(%v).subsetOf(%v) = %v; want %v", test.xl, test.yl, got, test.want)
		}
	}

func (h Names) Intersection(other Names) Names {
	result := make(Names, 0, len(h))
	for _, hHost := range h {
		for _, oHost := range other {
			if hHost.SubsetOf(oHost) {
				if !result.Contains(hHost) {
					result = append(result, hHost)
				}
			} else if oHost.SubsetOf(hHost) {
				if !result.Contains(oHost) {
					result = append(result, oHost)
				}
			}
		}
	}
	return result
}

	case x.typ == nil:
		return true // t ∈ 𝓤 == true
	}
	// ∅ ⊂ x ⊂ 𝓤

	u := t
	if x.tilde {
		u = under(u)
	}
	return Identical(x.typ, u)
}

// subsetOf reports whether x ⊆ y.
func (x *term) subsetOf(y *term) bool {
	// easy cases
	switch {
	case x == nil:
		return true // ∅ ⊆ y == true
	case y == nil:
		return false // x ⊆ ∅ == false since x != ∅
	case y.typ == nil:

	case x.typ == nil:
		return true // t ∈ 𝓤 == true
	}
	// ∅ ⊂ x ⊂ 𝓤

	u := t
	if x.tilde {
		u = under(u)
	}
	return Identical(x.typ, u)
}

// subsetOf reports whether x ⊆ y.
func (x *term) subsetOf(y *term) bool {
	// easy cases
	switch {
	case x == nil:
		return true // ∅ ⊆ y == true
	case y == nil:
		return false // x ⊆ ∅ == false since x != ∅
	case y.typ == nil: