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This lecture covers various types of relations, properties, and operations related to semi-groups, homomorphisms, isomorphisms, and machine equivalences in sequential machine theory. Concepts such as single-valued systems, groupoids, monoids, and closed binary operations are explained.
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Morphisms of State Machines Sequential Machine Theory Prof. K. J. Hintz Department of Electrical and Computer Engineering Lecture 8 Updated and adapted by Marek Perkowski
Partition of a Set • Properties • pi are called “pi-blocks” of a partition, (A)
Types of Relations • Partial, Binary, Single-Valued System • Groupoid • SemiGroup • Monoid • Group
Groupoid • Closed Binary Operation • Partial, Binary, Single-Valued System with • It is defined on all elements of S x S • Not necessarily surjective
SemiGroup • An Associative Groupoid • Binary operation, e.g., multiplication • Closure • Associative • Can be defined for various operations, so sometimes written as
Closed Binary Operation • Division Is Not a Closed Binary Operation on the Set of Counting Numbers 6/3 = 2 = counting number 2/6 = ? = not a counting number • Division Is Closed Over the Set of Real Numbers.
Monoid Semigroup With an Identity Element, e.
Group Monoid With an Inverse
‘Morphisms’ Homomorphism (J&J) “A correspondence of a set D (the domain) with a set R (the range) such that each element of D determines a unique element of R [single-valued] and each element of R is the correspondent of at least one element of D.“ and...
Homomorphism “If operations such as multiplication, addition, or multiplication by scalars are defined for D and R, it is required that these correspond...” and...
Homomorphism “If D and R are groups (or semigroups) with the operation denoted by * and x corresponds to x’ and y corresponds to y’ then x * y must correspond to x’ * y’ “ • Product of Correspondence = Correspondence of product
Homomorphism • Correspondence must be • Single-valued: therefore at least a partial function • Surjective: each y in the R has at least one x in the D • Non-Injective: not one-to-one else isomorphism
Endomorphism • A ‘morphism’ which maps back onto itself • The range, R, is the same set as the domain, D, e.g., the real numbers. ‘morphism’ R=D
SmGp. HmMphsm. Example* *Larsen, Intro to Modern Algebraic Concepts, p. 53
SmGp. HmMphsm. Example* Is the relation • single-valued? • Each symbol of D maps to only one symbol of R • surjective? • Each symbol of R has a corresponding element in D • not-injective? • e and g4 correspond to the same symbol, 0
SmGp. HmMphsm. Example* Do the results of operations correspond? same
Isomorphism • An Isomorphism Is a Homomorphism Which Is Injective • Injective: One-to-One Correspondence • A relation between two sets such that pairs can be removed, one member from each set until both sets have been simultaneously exhausted
SemiGroup Isomorphism Injective Homomorphism
Isomorphism Example* • Define two groupoids • non-associative semigroups • groups without an inverse or identity element • SG1: A1 = { positive real numbers } *1 = multiplication = * • SG2: A2 = { positive real numbers } *2 = addition = + *Ginzberg, pg 10
Machine Isomorphisms • Input-output isomorphism, but usually abbreviated to just isomorphism • An I/O isomorphism exists between two machines, M1 and M2 if there exists a triple
Machine Isomorphisms Interpret
Homo- vice Iso- Morphism Reduction Homomorphism • Shows behavioral equivalence between machines of different sizes • Allows us to only concern ourselves with minimized machines (not yet decomposed, but fewest states in single machine) • If we can find one, we can make a minimum state machine
Homo- vice Iso- Morphism Isomorphism • Shows equivalence of machines of identical, but not necessarily minimal, size • Shows equivalence between machines with different labels for the inputs, states, and/or outputs
Block Diagram Isomorphism I1 I2 O2 O1 M2 O1 M1 I1
Block Diagram Isomorphism which is the same as the preceding state diagram and block diagram definitions therefore M1 and M2 are Isomorphic to each other
Machine Information • Since the Inputs and Outputs Can Be Mapped Through Isomorphisms Which Are Independent of the State Transitions, All of the State Change Information Is Maintained in the Isomorphic Machine • Isomorphic Machines Produce Identical Outputs
Machine Homomorphism • If alpha is injective, then have isomorphism • “State Behavior” assignment, • “Realization” of M1 • If alpha not injective • “Reduction Homomorphism”