Struct DegRevLex 

pub struct DegRevLex;

The graded reverse lexicographic order. This is the most important monomial order, since computing a Groebner basis w.r.t. this order is usually more efficient than for other orders. Also sometimes referred to as “grevlex”.

Concretely, this is the ordering of monomials we get by first comparing monomial degrees, and in case of a tie reverse the outcome of a lexicographic comparison, using a reversed order of variables.

Example

let poly_ring = MultivariatePolyRingImpl::new(StaticRing::<i64>::RING, 3);
let monomials_descending = [
    [2, 0, 0], // x1^2
    [1, 1, 0], // x1 x2
    [0, 2, 0], // x2^2
    [1, 0, 1], // x1 x3
    [0, 1, 1], // x2 x3
    [0, 0, 2], // x3^2
].into_iter().map(|m| poly_ring.create_monomial(m)).collect::<Vec<_>>();
for i in 1..6 {
    assert!(DegRevLex.compare(&poly_ring, &monomials_descending[i - 1], &monomials_descending[i]) == Ordering::Greater);
}

Trait Implementations

impl Clone for DegRevLex

fn clone(&self) -> DegRevLex

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for DegRevLex

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

Formats the value using the given formatter.

impl MonomialOrder for DegRevLex

fn as_any(&self) -> Option<&dyn Any>

Upcasts this reference to &dyn Any, which is sometimes required to compare monomial order objects of different types.

fn compare<P>( &self, ring: P, lhs: &PolyMonomial<P>, rhs: &PolyMonomial<P>, ) -> Ordering

where P: RingStore, P::Type: MultivariatePolyRing,

fn eq_mon<P>( &self, ring: P, lhs: &PolyMonomial<P>, rhs: &PolyMonomial<P>, ) -> bool

where P: RingStore, P::Type: MultivariatePolyRing,

Checks whether two monomials are equal.

fn is_same<O>(&self, rhs: &O) -> bool

where O: MonomialOrder,

Whether this order is the same as the given other order, i.e. MonomialOrder::compare() gives the same output on all inputs.

impl PartialEq for DegRevLex

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for DegRevLex

impl Eq for DegRevLex

impl GradedMonomialOrder for DegRevLex

impl StructuralPartialEq for DegRevLex