This book gives a modern presentation of modular operands and their role
in string field theory. The authors aim to outline the arguments from
the perspective of homotopy algebras and their operadic origin.
Part I reviews string field theory from the point of view of homotopy
algebras, including A-infinity algebras, loop homotopy (quantum
L-infinity) and IBL-infinity algebras governing its structure. Within
this framework, the covariant construction of a string field theory
naturally emerges as composition of two morphisms of particular odd
modular operads. This part is intended primarily for researchers and
graduate students who are interested in applications of higher algebraic
structures to strings and quantum field theory.
Part II contains a comprehensive treatment of the mathematical
background on operads and homotopy algebras in a broader context, which
should appeal also to mathematicians who are not familiar with string
theory.