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e31d211468
Tool for studying combinatorial aspects of Coxeter group theory http://math.univ-lyon1.fr/~ducloux/coxeter/coxeter3/english/coxeter3_e.html Needed for #14155
101 lines
2.3 KiB
Diff
101 lines
2.3 KiB
Diff
From 0c8eb9cdba9cc54415fc4f808f71f1e3e2323e85 Mon Sep 17 00:00:00 2001
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From: Jeroen Demeyer <jdemeyer@cage.ugent.be>
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Date: Mon, 26 Feb 2018 14:43:08 +0100
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Subject: [PATCH] Add Sage interface
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---
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sage.cpp | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
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sage.h | 22 ++++++++++++++++++++++
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2 files changed, 77 insertions(+)
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create mode 100644 sage.cpp
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create mode 100644 sage.h
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diff --git a/sage.cpp b/sage.cpp
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new file mode 100644
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index 0000000..503654d
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--- /dev/null
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+++ b/sage.cpp
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@@ -0,0 +1,55 @@
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+/*
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+ Coxeter version 3.0 Copyright (C) 2009 Mike Hansen
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+*/
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+
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+#include "sage.h"
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+
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+namespace sage {
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+
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+ void interval(List<CoxWord>& list, CoxGroup& W, const CoxWord& g, const CoxWord& h)
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+
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+ /*
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+ Return a list of the elements in the Bruhat interval between g and h.
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+ Note that this assumes that g and h are in order.
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+ */
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+ {
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+ if (not W.inOrder(g,h)) {
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+ return;
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+ }
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+
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+ W.extendContext(h);
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+
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+ CoxNbr x = W.contextNumber(g);
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+ CoxNbr y = W.contextNumber(h);
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+
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+ BitMap b(W.contextSize());
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+ W.extractClosure(b,y);
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+
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+ BitMap::ReverseIterator b_rend = b.rend();
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+ List<CoxNbr> res(0);
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+
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+ for (BitMap::ReverseIterator i = b.rbegin(); i != b_rend; ++i)
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+ if (not W.inOrder(x,*i)) {
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+ BitMap bi(W.contextSize());
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+ W.extractClosure(bi,*i);
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+ CoxNbr z = *i; // andnot will invalidate iterator
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+ b.andnot(bi);
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+ b.setBit(z); // otherwise the decrement will not be correct
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+ } else
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+ res.append(*i);
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+
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+ schubert::NFCompare nfc(W.schubert(),W.ordering());
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+ Permutation a(res.size());
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+ sortI(res,nfc,a);
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+
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+ list.setSize(0);
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+ for (size_t j = 0; j < res.size(); ++j) {
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+ CoxWord w(0);
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+ W.schubert().append(w, res[a[j]]);
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+ list.append(w);
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+ }
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+
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+ return;
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+ }
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+
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+}
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diff --git a/sage.h b/sage.h
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new file mode 100644
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index 0000000..fed0a7a
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--- /dev/null
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+++ b/sage.h
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@@ -0,0 +1,22 @@
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+/*
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+ Coxeter version 3.0 Copyright (C) 2009 Mike Hansen
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+*/
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+
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+#ifndef SAGE_H /* guard against multiple inclusions */
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+#define SAGE_H
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+
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+#include "globals.h"
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+#include "coxgroup.h"
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+#include "coxtypes.h"
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+#include "schubert.h"
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+#include "list.h"
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+
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+namespace sage {
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+ using namespace coxeter;
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+ using namespace coxtypes;
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+ using namespace list;
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+
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+ void interval(List<CoxWord>& result, CoxGroup& W, const CoxWord& g, const CoxWord& h);
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+}
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+
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+#endif
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