close Warning: Can't synchronize with repository "(default)" (The repository directory has changed, you should resynchronize the repository with: trac-admin $ENV repository resync '(default)'). Look in the Trac log for more information.

source: branches/f4grobner/pair-queue.lisp@ 3939

Last change on this file since 3939 was 3939, checked in by Marek Rychlik, 8 years ago

* empty log message *

File size: 5.5 KB
Line 
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 :utils)
24 (:export "CRITICAL-PAIR"
25 "CRITICAL-PAIR-FIRST"
26 "CRITICAL-PAIR-SECOND"
27 "MAKE-PAIR-QUEUE"
28 "PAIR-QUEUE-INITIALIZE"
29 "PAIR-QUEUE-INSERT"
30 "PAIR-QUEUE-REMOVE"
31 "PAIR-QUEUE-SIZE"
32 "PAIR-QUEUE-EMPTY-P"
33 "SET-PAIR-HEURISTIC"
34 )
35 (:documentation "Critical pair queue implementation. The pair queue is a list of critical
36pairs, ordered by some partial order. Pair queue is a kind of priority queue.")
37 )
38
39(in-package :pair-queue)
40
41(defclass critical-pair ()
42 ((first :initform nil :initarg :first :accessor critical-pair-first :type poly)
43 (second :initform nil :initarg :second :accessor critical-pair-second :type poly))
44 (:documentation "Represents a critical pair, i.e. a pair of two polynomials. The derived
45classes may add extra data used in computing the order of critical pairs."))
46
47(defmethod print-object ((self critical-pair) stream)
48 (print-unreadable-object (self stream :type t :identity t)
49 (with-accessors ((first critical-pair-first)
50 (second critical-pair-second))
51 self
52 (format stream "FIRST=~A SECOND=~A"
53 first second))))
54
55(defclass selection-strategy ()
56 ((pair-key-fn :initform (error "Must specify PAIR-KEY-FN") :initarg :pair-key-fn :accessor pair-key-fn)
57 (pair-order-fn :initform (error "Must specify PAIR-ORDER-FN") :initarg :pair-order-fn :accessor pair-order-fn))
58 (:documentation "Represents a critical pair selection strategy. The
59two ingredients of a strategy is a function PAIR-KEY-FUNCTION which
60computes a key from the critical pair, which can be any type of data,
61and a function PAIR-ORDER-FN used to compaire the calculated keys to
62determine which pair is more promising and should be considered first."))
63
64(defmethod print-object ((self selection-strategy) stream)
65 (print-unreadable-object (self stream :type t :identity t)
66 (with-accessors ((pair-key-fn pair-key-fn)
67 (pair-order-fn pair-order-fn))
68 self
69 (format stream "PAIR-KEY-FN=~A PAIR-ORDER-FN=~A"
70 pair-key-fn pair-order-fn))))
71
72(defclass normal-selection-strategy (selection-strategy)
73 ((pair-key-fn :initform #'(lambda (p q) (universal-lcm (leading-monomial p) (leading-monomial q))))
74 (pair-order-fn :initform #'lex>))
75 (:documentation "The normal selection strategy for a given monomial order MONOMIAL-ORDER-FN. A pair
76with the minimal LCM of leading monomials is selected."))
77
78(defclass min-total-degree-strategy (selection-strategy)
79 ((pair-key-fn :initform #'(lambda (p q) (total-degree (universal-lcm (leading-monomial p) (leading-monomial q)))))
80 (pair-order :initform #'<))
81 (:documentation "Make a selection strategy where a pair with a
82minimum total degree of LCM of leading monomials is selected."))
83
84(defclass minimal-length-strategy (selection-strategy)
85 ((pair-key-fn :initform #'(lambda (p q) (+ (poly-length p) (poly-length q))))
86 (pair-order :initform #'<))
87 (:documentation "Make a selection strategy where a pair with the minimum combined length of both
88polynomials is selected."))
89
90(defclass critical-pair-queue (selection-strategy)
91 ((pq :type priority-queue)))
92
93(defmethod initialize-instance :after ((self critical-pair-queue) &key)
94 (with-slots (pair-key-fn pair-order-fn pq)
95 (setf pq (make-priority-queue
96 :element-type 'critical-pair
97 :element-key #'(lambda (pair) (funcall pair-key-fn (critical-pair-first pair) (critical-pair-second pair)))
98 :test pair-order-fn))))
99
100(defun pair-queue-initialize (pq f start
101 &aux
102 (s (1- (length f)))
103 (b (nconc (makelist (make-instance 'critical-pair :first (elt f i) :second (elt f j))
104 (i 0 (1- start)) (j start s))
105 (makelist (make-instance 'critical-pair :first (elt f i) :second (elt f j))
106 (i start (1- s)) (j (1+ i) s)))))
107 "Initializes the priority for critical pairs. F is the initial list of polynomials.
108START is the first position beyond the elements which form a partial
109grobner basis, i.e. satisfy the Buchberger criterion."
110 (declare (type priority-queue pq) (type fixnum start))
111 (dolist (pair b pq)
112 (priority-queue-insert pq pair)))
113
114(defun pair-queue-insert (b pair)
115 (priority-queue-insert b pair))
116
117(defun pair-queue-remove (b)
118 (priority-queue-remove b))
119
120(defun pair-queue-size (b)
121 (priority-queue-size b))
122
123(defun pair-queue-empty-p (b)
124 (priority-queue-empty-p b))
125
126
127
128
Note: See TracBrowser for help on using the repository browser.