How does symbolic logic distinguish different meanings of the word “is”?

In symbolic logic, particularly within the tradition established by 20th-century logicians like Gottlob Frege and Bertrand Russell, the natural-language verb "is" is considered multiply ambiguous. To eliminate this ambiguity, symbolic logic assigns distinct logical forms to its various uses:123

• Predication: Used to attribute a property to a subject (e.g., "Tarzan is blond"), it is represented as a predicate applied to an argument, such as $B(t)$.13
• Identity: Used to express that two terms refer to the same entity (e.g., "Clark Kent is Superman"), it is symbolized using the identity sign, as in $c=s$.13
• Existence: Used to assert that an entity exists (e.g., "Zeus is"), it is expressed using the existential quantifier, such as $(\exists x)(x=z)$.13
• Class-inclusion: Used to state that one class is a subset of another (e.g., "The whale is a mammal"), it is represented using the universal quantifier and the conditional, such as $(\forall x)(W(x)\supset M(x))$.13

While this "Frege-Russell ambiguity" claim is a hallmark of modern formal logic, some philosophers argue that "is" may not be genuinely ambiguous, but rather context-dependent.23