====== Terminology (MathExi)======

  - term type
  - set/collection group category
  - injecture surjecture
  - isomorphism monomorphism epimorphism
  - duality
  - product/coproduct pullback/pushout equalizer/coequalizer limit/colimit
  - initial-object/ terminal-object
  - functor natural-transformation adjoint
  - monoid 
  - monad/comonad
  - $\alpha$-convesion $\beta$-reduction $\eta$-convesion
  - {free, bound, binding}-occurrence
  - $\lambda$-cube