Attachment and the three poisons Is there any dependence between these? My understanding is that ignorance is the main cause for samsara (the first of the 12 links of dependent origination). Ignorance meaning not recognizing our true condition. But is attachment a necessary condition for anger? For greed?
Ignorance meaning not recognizing our true condition.

More particularly:


  And what, bhikshus, is ignorance (avijjā)?
  
  
  Not knowing suffering, 
  not knowing the arising of suffering, 
  not knowing the ending of suffering, 
  not
  knowing the path leading to the ending of suffering. 
  
  
  This is called ignorance.


(Paṭicca,samuppada) Vibhanga Sutta

My understanding is that ignorance is the main cause for samsara

Ignorance sets the ball rolling. Ignorance is one prace you can break Dependent Origination by understanding the 4 Noble Truths at the experiential level. Hence it is one condition for the samsaric existence.

Other place DO can be broken is but not letting craving arise which results from your reaction to sensations due to contact.

Is there any dependence between these?


  (1) the latent tendency to lust reinforced by being attached to pleasant feelings;
  
  (2) the latent tendency to aversion reinforced by rejecting painful feelings;
  
  (3) the latent tendency to ignorance reinforced by ignoring neutral feelings.


Pahāna Sutta

But is attachment a necessary condition for anger? For greed?

Attachment or it's flavours are necessary conditions for greed. Anger is a form of grief hence you can include anger also.


  
  From endearment springs grief, from endearment springs fear. For one who is wholly free from endearment there is no grief, whence then fear?
  From affection springs grief, from affection springs fear. For one who is wholly free from affection there is no grief, whence then fear?
  From attachment springs grief, from attachment springs fear. For one who is wholly free from attachment there is no grief, whence then fear?
  From lust springs grief, from lust springs fear. For one who is wholly free from craving there is no grief; whence then fear?
  From craving springs grief, from craving springs fear. For one who is wholly free from craving there is no grief; whence then fear?
  


Dhammapada - Piyavagga