(block) gerschgorin theorem

Ⅱ theorem

3-D potential theorem

3G theorem

3σ theorem

4-color theorem

a fixed-point theorem in double cones

a theorem of alternative

Able’s theorem

acoustical reciprocity theorem

addition theorem

addition theorem of probability

additive theorem

adiabatic evolution theorem

Aitken theorem

almighty approaching theorem

Almost fixed point theorem

Almost sure central limit theorem

Alternative theorem

Altman fixed point theorem