Hoàng Xuân Sính’s Thesis
Posted by John Baez
During the Vietnam war, Grothendieck taught math to the Hanoi University mathematics department staff, out in the countryside. Hoàng Xuân Sính took notes and later did a PhD with him — by correspondence, under very difficult conditions!
I wrote about this here a while back, and on that basis got invited to contribute a paper to a volume in honor of her 90th birthday. Here’s a draft:
I’d love corrections or suggestions.
I’m trying to minimize the technical details but still give a sense of what she actually did in her thesis. So, besides explaining some of the history, I’m also trying to give a gentle introduction to 2-groups. That’s why I’m not taking a very sophisticated point of view…. or at least that’s my excuse.
There are a lot of historical puzzles here, and I wish I had a time machine to investigate them, or at least a year or two to interview people.
Poem for Madame Hoang
As this is tangentially about Grothendieck, I thought it might be appropriate to share a poem I wrote as an eulogy for Grothendieck when he passed away. And then I had the brighter idea to write a poem for Madame Hoang’s birthday - it seemed much more appropriate.
Hoang’s Song
Avoid myth, avoid illusion
Seek the real, seek the authentic
Even in ruins
Even in fiery carnage
Where once bamboo groves swayed
In monsoon squalls
Where once bamboo villages filled
With the laughter of children
The sky, once a river of rain
Or a haze of quiet summer heat
Where dragon flies dream
Is now a river of fire, of flame
They aim to enslave us
But we will not be enslaved
They aim to starve us
But we will not be swayed
A drop of rain can chisel a cliff
And a small chisel in the right place
Can crack open a mountain
And the stars are cracks in heavens night
That let the far distant light in
Such splendid light that enchanted
Those watchers of the skies above
And the skies within and without
I read by the light of a kerosene lamp
Sometimes sooty black the light by which
The crystal realm is illuminated is inscribed
A spiral pirouettes on a pole and threads
An axis and dances the spheres
Hieroglyphs that reveal the crystal contours
The beat of a drum that tattoos the pattern
These are distant peaks that few see
But here, the water runs as natural
As water falls elsewhere
It cleans and it nourishes
Seek myth, and be a myth maker
Seek the real, and make new realities
A pebble dropped into a middle of an ocean
Can rock the whole ocean.
We are descendents of the dragon
And our swords are carved whole from jade
And do not fade even in the fading evening light
And I am dragon’s daughter
And my dragon’s eyes
Sees into the depths of all things