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hyperrogue/rogueviz/janko.cpp

141 lines
3.3 KiB
C++

/* explore the Janko group J1: https://en.wikipedia.org/wiki/Janko_group_J1 */
#include "rogueviz.h"
#if !ISWEB
namespace hr {
eGeometry gJanko1(eGeometry(-1));
struct jmatrix : array<array<int, 7>, 7> {
jmatrix operator * (const jmatrix other) {
jmatrix res;
for(int a=0; a<7; a++)
for(int b=0; b<7; b++)
res[a][b] = 0;
for(int a=0; a<7; a++)
for(int b=0; b<7; b++)
for(int c=0; c<7; c++)
res[a][c] += self[a][b] * other[b][c];
for(int a=0; a<7; a++)
for(int b=0; b<7; b++)
res[a][b] %= 11;
return res;
}
};
vector<jmatrix> jms;
std::map<jmatrix, int> ids;
jmatrix J, Z, id;
int get_id(const jmatrix& m) {
if(ids.count(m)) return ids[m];
ids[m] = isize(jms);
jms.push_back(m);
return isize(jms)-1;
}
void build_group(const jmatrix& m) {
if(ids.count(m)) return;
jmatrix m2 = m;
for(int a=0; a<7; a++) { get_id(m2); m2 = m2 * J; }
}
void build() {
for(int a=0; a<7; a++)
for(int b=0; b<7; b++) J[a][b] = ((a+1-b)%7 == 0) ? 1 : 0;
int v[49] = {
0, 4, 0, 3, 9, 2, 1,
4, 0, 4, 3, 7, 1, 3,
0, 4, 10, 6, 9, 8, 1,
3, 3, 6, 1, 7, 6, 9,
9, 7, 9, 7, 0, 9, 10,
2, 1, 8, 6, 9, 2, 3,
1, 3, 1, 9, 10, 3, 8,
/* -3,+2,-1,-1,-3,-1,-3,
-2,+1,+1,+3,+1,+3,+3,
-1,-1,-3,-1,-3,-3,+2,
-1,-3,-1,-3,-3,+2,-1,
-3,-1,-3,-3,+2,-1,-1,
+1,+3,+3,-2,+1,+1,+3,
+3,+3,-2,+1,+1,+3,+1*/
};
int a = 0;
for(auto& row: Z) for(auto& i: row) { i = v[a++]; if(i < 0) i += 11; }
for(int a=0; a<7; a++) for(int b=0; b<7; b++) id[a][b] = a==b ? 1 : 0;
build_group(id);
for(int k=0; k<isize(jms); k++) {
build_group(jms[k] * Z);
}
/*
B = Z
J = A * B
A = J * B * B
*/
println(hlog, "order = ", isize(jms));
}
void experiment() {
for(int ia=1; ia<isize(jms); ia++) if(jms[ia] * jms[ia] == id)
for(int ib=1; ib<isize(jms); ib++) if(jms[ib] * jms[ib] * jms[ib] == id) {
jmatrix u = jms[ia] * jms[ib];
if(u != J) continue;
if(u == id) continue;
jmatrix up = u, ubp = u;
ubp = ubp * ubp; up = up * ubp;
ubp = ubp * ubp; up = up * ubp;
if(up != id) continue;
println(hlog, "found: ", tie(ia, ib));
for(auto& row: jms[ia]) {
for(auto& i: row) print(hlog, format("%2d, ", i));
println(hlog);
}
}
exit(1);
}
auto h = addHook(hooks_newmap, 0, [] {
if(geometry == gJanko1) {
build();
vector<int> connections;
connections.clear();
for(int i=0; i<isize(jms); i++) connections.push_back(get_id(jms[i] * Z));
println(hlog, connections);
return (hrmap*) new quotientspace::hrmap_quotient(connections);
}
return (hrmap*) nullptr;
});
void create_janko() {
if(gJanko1 != eGeometry(-1)) return;
ginf.push_back(ginf[gNormal]);
gJanko1 = eGeometry(isize(ginf) - 1);
// variation = eVariation::pure;
auto& gi = ginf.back();
gi.flags = qANYQ | qCLOSED | qEXPERIMENTAL;
gi.quotient_name = "Janko";
gi.shortname = "Janko";
gi.menu_displayed_name = "Janko group J1";
}
auto shot_hooks = arg::add3("-janko1x", [] { build(); experiment(); })
+ addHook(hooks_initialize, 100, create_janko);
}
#endif