Changes in Core Maude:

• Optimizations
• More compact representation for terms and automata - visible memory savings may be small because memory usage is usually dominated by the CFG parser.
• Parse time processing of modules greatly optimized.
• File handling optimized; fewer expensive system calls.
• Equation matching infrastructure optimized.
• A and AU matching optimized.
• AU theory normalization optimized.
• Bug fixes
• Sort test operators print correctly.
• Pretty printer handles ad-hoc overloading between built in constants and user constants correctly.
• New features
• ~ and ~user expansions are performed for path names.
• Parentheses and polymorphic operators are now only recognized for connected sort components that don't contain a bubble.

• The transformation of object-oriented modules to system modules, and the  flattening of such modules, has been greatly optimized.
• The transformation applied on rules in object-oriented modules is now also applied to membership axioms and equations, so objects in them can be given following the same conventions (not exhausting of attributes, being applicable to the objects in subclasses, etc).
• Two of the syntactic restrictions for Full Maude, explained in Section 3.5  of the manual (January 1999), have been removed, namely some context is added  for the parsing of bubbles (unexpected ambiguities are therefore avoided) and  entire bubbles can be enclosed in parentheses without generating the harmless ambiguities.
• There are two new module expressions available. The first one is the union operator _+_. One can have now importation declarations as, for example,

pr NAT * (sort Nat to Foo) + BOOL + LIST[Nat] .

The second one is a "tuple generator." One can have declarations as

pr TUPLE(n)[V_1, ..., V_n] .

for any nonzero natural number n and views V_1 ... V_n with TRIV as source theory. The module expression TUPLE(3), for example, generates a parameterized functional module of the form

fmod TUPLE(3)[C1 :: TRIV, C2 :: TRIV, C3 :: TRIV] is
    sorts 3Tuple .
    op p1_ : 3Tuple -> Elt.C1 .
    op p2_ : 3Tuple -> Elt.C2 .
    op (_,_,_) : Elt.C1 Elt.C2 Elt.C3 -> 3Tuple .
    op p3_ : 3Tuple -> Elt.C3 .
    var E1 : Elt.C1 .
    var E2 : Elt.C2 .
    var E3 : Elt.C3 .
    eq p1(E1, E2, E3) = E1 .
    eq p2(E1, E2, E3) = E2 .
    eq p3(E1, E2, E3) = E3 .
endfm

• A bug in the evaluation of renaming module expressions has been fixed.
• There was an inconsistency between the CONFIGURATION module in the manual and the one used by the system.