en.wikipedia.org/wiki/Associative_property

In general, parentheses must be used to indicate the order of evaluation if a non-
associative operation ...

www.computerhope.com/jargon/a/assooper.htm

Computer dictionary definition for what associative operation means including
related links, information, and terms.

www.mathwords.com/a/associative_operation.htm

Any operation ⊕ for which (a⊕b)⊕c = a⊕(b⊕c) for all values of a, b, and c.
Addition and multiplication are both associative. Subtraction and division are not.

www.purplemath.com/modules/numbprop.htm

Discusses the Commutative, Associative, and Distributive Properties (or ... to both
addition and multiplication, too, but it refers to both of the operations within just ...

www.math.csusb.edu/notes/binop/node4.html

Dec 3, 1996 ... A binary operation is said to be associative if for all elements a, b and c we have
tex2html_wrap_inline139 . For convenience let's drop the ...

math.stackexchange.com/questions/924159/prove-that-an-associative-operation-is-a-structural-property

Sep 8, 2014 ... First off how does one prove that an operation ∗ is a structural property and how
is this different from just proving an isomorphism? My main ...

math.stackexchange.com/questions/327422/are-all-algebraic-commutative-operations-always-associative

Mar 11, 2013 ... I know that there are many algebraic associative operations which are
commutative and which are not commutative. for example multiplications ...

math.stackexchange.com/questions/168663/is-there-an-easy-way-to-see-associativity-or-non-associativity-from-an-operation

Jul 9, 2012 ... Most properties of a single binary operation can be easily read of from the ...
doing explicitly all the calculations) if an operation is associative?

faculty.atu.edu/mfinan/4033/absalg3.pdf

Example 3.1. Addition and multiplication are binary operations on the set Z of
integers ... A binary operation ∗ on a set S is said to be associative if it satisfies
the.

mathforum.org/library/drmath/view/72185.html

I don't agree that subtraction and division are not commutative operations. If we
define a - b as a + (-b), then it commutes correctly into (-b) + a.