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Element

Element of WMA link

Element[expr, domain]

returns True if expr is an element of domain

Element[$expr_1$|$expr_2$|..., domain]

returns True if all the $expr_i$ belongs to domain, and False if one of the items doesn't.

Check if $3$ and a are both integers. If a is not defined, then Element reduces the condition:

• • Element[3 | a, Integers]

Notice that standard domain names (Primes, Integers, Rationals, Algebraics, Reals, Complexes, and Booleans) are in plural form. If a singular form is used, a warning is shown:

• • Element[a, Real]