In mathematics, infinity is the conceptual expression of such a numberless number. It is often symbolized by the lemniscate (also known as the lemniscate of Bernoulli), which looks something like the numeral 8 written sideways (). This symbol for infinity was first used in the 1600s by the mathematician John Wallis.
An epic is a poem; most epics started as oral tales that were passed down from generation to generation (often in the form of songs), which is why they're poems. A legend and a myth are more similar, but a myth most often explains something about the universe. So while there might be a legend about a man who slayed all the dragons, a myth would be about the man who caused it to rain, or how humans were created. Those are the basics differences.
An epic is traditionally a genre of poetry, known as epic poetry. However, in modern terms, epic is often extended to other art forms, such as epic theatre, films, music, novels, stage play, television series, and video games, wherein the story has a theme of grandeur and heroism, just as in epic poetry.