Theory, mathematics and psychology, suggestion or statement shown. In geometry, a proposal is often considered a problem (construction to be done) or a theorem (a statement to be proved). The statement "When two lines meet, the vertical angles are equal," for example, is the theorem. The basic theory of algebra confirms that all (complex) polynomial equations in one variation have at least one root or solution. The Greeks also realized that there was a suggestion between the scholar and the problem, the porism, aimed at producing or acquiring what was proposed.