fun with variance

using System;

interface IFactory<out T>
{
    T Create();
}
static class P
{
    static void Main()
    {
        IFactory<Base> ambiguous = new MixedMidFactory();
        Console.WriteLine(ambiguous.Create()); // MidA

        ambiguous = new MixedMidFactoryReversed();
        Console.WriteLine(ambiguous.Create()); // MidB

        ambiguous = new MixedMidFactoryFull();
        Console.WriteLine(ambiguous.Create()); // Base

        ambiguous = new TwoTierFactory();
        Console.WriteLine(ambiguous.Create()); // MidA

        ambiguous = new TwoTierFactoryReversed();
        Console.WriteLine(ambiguous.Create()); // SuperMidA

        ambiguous = new TwoTierFactoryFull();
        Console.WriteLine(ambiguous.Create()); // Base
    }
}

class Base { }
class MidA : Base { }
class MidB : Base { }
class SuperMidA : MidA { }

// implements factories for two subclasses in separate hierarchies
class MixedMidFactory : IFactory<MidA>, IFactory<MidB>
{
    MidA IFactory<MidA>.Create() => new MidA();
    MidB IFactory<MidB>.Create() => new MidB();
}

// only difference to MixedMidFactory is interface declaration order
class MixedMidFactoryReversed : IFactory<MidB>, IFactory<MidA>
{
    MidA IFactory<MidA>.Create() => new MidA();
    MidB IFactory<MidB>.Create() => new MidB();
}

// like MixedMidFactoryReversed, but also implements the actual type requested
class MixedMidFactoryFull : IFactory<MidA>, IFactory<MidB>, IFactory<Base>
{
    MidA IFactory<MidA>.Create() => new MidA();
    MidB IFactory<MidB>.Create() => new MidB();
    Base IFactory<Base>.Create() => new Base();
}

// implements factories for two subclasses in the same hierarchy
class TwoTierFactory : IFactory<MidA>, IFactory<SuperMidA>
{
    MidA IFactory<MidA>.Create() => new MidA();
    SuperMidA IFactory<SuperMidA>.Create() => new SuperMidA();
}

// only difference to TwoTierFactory is interface declaration order
class TwoTierFactoryReversed : IFactory<SuperMidA>, IFactory<MidA>
{
    MidA IFactory<MidA>.Create() => new MidA();
    SuperMidA IFactory<SuperMidA>.Create() => new SuperMidA();
}

// like TwoTierFactoryReversed, but also implements the actual type requested
class TwoTierFactoryFull : IFactory<SuperMidA>, IFactory<MidA>, IFactory<Base>
{
    MidA IFactory<MidA>.Create() => new MidA();
    SuperMidA IFactory<SuperMidA>.Create() => new SuperMidA();
    Base IFactory<Base>.Create() => new Base();
}