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source: branches/f4grobner/pair-queue.lisp@ 3953

Last change on this file since 3953 was 3952, checked in by Marek Rychlik, 8 years ago

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1;;; -*- Mode: Lisp -*-
2;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
3;;;
4;;; Copyright (C) 1999, 2002, 2009, 2015 Marek Rychlik <rychlik@u.arizona.edu>
5;;;
6;;; This program is free software; you can redistribute it and/or modify
7;;; it under the terms of the GNU General Public License as published by
8;;; the Free Software Foundation; either version 2 of the License, or
9;;; (at your option) any later version.
10;;;
11;;; This program is distributed in the hope that it will be useful,
12;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
13;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14;;; GNU General Public License for more details.
15;;;
16;;; You should have received a copy of the GNU General Public License
17;;; along with this program; if not, write to the Free Software
18;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19;;;
20;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
21
22(defpackage "PAIR-QUEUE"
23 (:use :cl :priority-queue :monom :polynomial :symbolic-polynomial :utils)
24 (:export "CRITICAL-PAIR"
25 "CRITICAL-PAIR-FIRST"
26 "CRITICAL-PAIR-SECOND"
27 "CRITICAL-PAIR-QUEUE"
28 "PAIR-QUEUE-INSERT"
29 "PAIR-QUEUE-REMOVE"
30 "PAIR-QUEUE-SIZE"
31 "PAIR-QUEUE-EMPTY-P"
32 "SET-PAIR-HEURISTIC"
33 )
34 (:documentation "Critical pair queue implementation. The pair queue is a list of critical
35pairs, ordered by some partial order. Pair queue is a kind of priority queue.")
36 )
37
38(in-package :pair-queue)
39
40(defclass critical-pair ()
41 ((first :initform nil :initarg :first :accessor critical-pair-first :type poly)
42 (second :initform nil :initarg :second :accessor critical-pair-second :type poly))
43 (:documentation "Represents a critical pair, i.e. a pair of two polynomials. The derived
44classes may add extra data used in computing the order of critical pairs."))
45
46(defmethod print-object ((self critical-pair) stream)
47 (print-unreadable-object (self stream :type t :identity t)
48 (with-accessors ((first critical-pair-first)
49 (second critical-pair-second))
50 self
51 (format stream "FIRST=~A SECOND=~A"
52 first second))))
53
54(defclass selection-strategy ()
55 ((pair-key-fn :initform #'(lambda (p q) (universal-lcm (leading-monomial p) (leading-monomial q))) :initarg :pair-key-fn :accessor pair-key-fn)
56 (pair-order-fn :initform #'lex> :initarg :pair-order-fn :accessor pair-order-fn))
57 (:documentation "Represents the normal critical pair selection
58strategy. The two ingredients of a strategy is a function
59PAIR-KEY-FUNCTION which computes a key from the critical pair, which
60can be any type of data, and a function PAIR-ORDER-FN used to compaire
61the calculated keys to determine which pair is more promising and
62should be considered first. The normal selection strategy for a given
63monomial order PAIR-ORDER-FN consists in selecting the pair with the
64minimal LCM of leading monomials first."))
65
66(defmethod print-object ((self selection-strategy) stream)
67 (print-unreadable-object (self stream :type t :identity t)
68 (with-accessors ((pair-key-fn pair-key-fn)
69 (pair-order-fn pair-order-fn))
70 self
71 (format stream "PAIR-KEY-FN=~A PAIR-ORDER-FN=~A"
72 pair-key-fn pair-order-fn))))
73
74(defclass min-total-degree-strategy (selection-strategy)
75 ((pair-key-fn :initform #'(lambda (p q) (total-degree (universal-lcm (leading-monomial p) (leading-monomial q)))))
76 (pair-order-fn :initform #'<))
77 (:documentation "Make a selection strategy where a pair with a
78minimum total degree of LCM of leading monomials is selected."))
79
80(defclass minimal-length-strategy (selection-strategy)
81 ((pair-key-fn :initform #'(lambda (p q) (+ (poly-length p) (poly-length q))))
82 (pair-order-fn :initform #'<))
83 (:documentation "Make a selection strategy where a pair with the minimum combined length of both
84polynomials is selected."))
85
86(defclass critical-pair-queue (selection-strategy)
87 ((pq :initform nil :initarg :pq :accessor pq :type priority-queue)))
88
89(defmethod initialize-instance :after ((self critical-pair-queue) &key (poly-list nil) (start 1))
90 "Initializes the priority for critical pairs. POLY-LIST is the initial list of polynomials.
91START is the first position beyond the elements which form a partial
92grobner basis, i.e. satisfy the Buchberger criterion."
93 (with-accessors ((pair-key-fn pair-key-fn)
94 (pair-order-fn pair-order-fn)
95 (pq pq))
96 self
97 (setf pq (make-priority-queue
98 :element-type 'critical-pair
99 :element-key #'(lambda (pair) (funcall pair-key-fn (critical-pair-first pair) (critical-pair-second pair)))
100 :test pair-order-fn))
101 (let* ((s (1- (length poly-list)))
102 (b (nconc (makelist (make-instance 'critical-pair :first (elt poly-list i) :second (elt poly-list j))
103 (i 0 (1- start)) (j start s))
104 (makelist (make-instance 'critical-pair :first (elt poly-list i) :second (elt poly-list j))
105 (i start (1- s)) (j (1+ i) s)))))
106 (dolist (pair b pq)
107 (priority-queue-insert pq pair)))
108 ))
109
110(defmethod print-object ((self critical-pair-queue) stream)
111 (print-unreadable-object (self stream :type t :identity t)
112 (with-accessors ((pair-key-fn pair-key-fn)
113 (pair-order-fn pair-order-fn)
114 (pq pq))
115 self
116 (format stream "PAIR-KEY-FN=~A PAIR-ORDER-FN=~A PQ=~A"
117 pair-key-fn pair-order-fn pq))))
118
119
120
121(defun pair-queue-insert (b pair)
122 (priority-queue-insert b pair))
123
124(defun pair-queue-remove (b)
125 (priority-queue-remove b))
126
127(defun pair-queue-size (b)
128 (priority-queue-size b))
129
130(defun pair-queue-empty-p (b)
131 (priority-queue-empty-p b))
132
133
134
135
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