Struct WInstanceHom 

pub struct WInstanceHom {
    pub node_map: HashMap<u32, u32>,
}

A homomorphism between two W-type instances of the same schema.

The map sends each node of the domain instance to a node of the codomain instance. A well-formed homomorphism preserves anchors, arcs, fans, and the root; check verifies these conditions.

Fields

node_map: HashMap<u32, u32>

Node map: domain node id to codomain node id.

Implementations

impl WInstanceHom

pub const fn new(node_map: HashMap<u32, u32>) -> Self

Build a homomorphism from an explicit node map.

pub fn identity(instance: &WInstance) -> Self

The identity homomorphism on instance (each node maps to itself).

pub fn check(&self, dom: &WInstance, cod: &WInstance) -> Result<(), HomError>

Verify that this homomorphism from dom to cod preserves the W-type structure.

Checks, in order: totality of the node map over dom’s nodes; existence of every image in cod; anchor preservation; arc naturality (each domain arc maps to a codomain arc of the same edge); fan naturality; and root preservation.

Errors

Returns the first HomError encountered.

pub fn compose(&self, other: &Self) -> Result<Self, HomError>

Compose two homomorphisms: self from A to B followed by other from B to C, yielding a homomorphism from A to C.

Errors

Returns HomError::ComposeNodeMismatch if some image of self is outside the domain of other.

pub fn is_isomorphism(&self, dom: &WInstance, cod: &WInstance) -> bool

Returns true iff this homomorphism from dom to cod is an isomorphism: a structure-preserving bijection whose inverse is also structure preserving.

Trait Implementations

impl Clone for WInstanceHom

fn clone(&self) -> WInstanceHom

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for WInstanceHom

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for WInstanceHom

fn default() -> WInstanceHom

Returns the “default value” for a type.

impl Eq for WInstanceHom

impl PartialEq for WInstanceHom

fn eq(&self, other: &WInstanceHom) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for WInstanceHom