: The present thesis introduces and studies some aspects of analysis on a left; MARGIN: 0cm 0cm 10pt; unicode-bidi: embed; DIRECTION: ltr" dir=ltr multipliers $T : \\R^*\\longrightarrow \\R^*$ , weakly compact operators $L_f : \\A\\longrightarrow \\R$ , involutions $* : \\R^*\\longrightarrow \\R^*$ , topological invariant means $ {\\sf M} : \\R\\longrightarrow {\\ C}$ , derivations $D : \\A\\longrightarrow \\X^*$ , representations $\\pi : \\R^*\\longrightarrow B(\\h)$ , stable states $\\si : B(\\h)\\longrightarrow {\\ C}$ .