92 R.VOREADOU

principal choice of arguments, 79

principal component, 79

proper E-graph, 31

proper shape, vii

quasi-closed category, 22

quasi-inverse (of an E-graph), 41

rank, xiv

reduced (#2),(#4),(#5), 39

reduced (**4) , 55

reduced (#*2) , (#*4),(#*5), 48

shape, viii

simple E-graph, 42

simple relative (of an E-graph), 42

simple shape, 41

simplification of a shape, 41

string of formal instances of ..., x

trivial arrow (between shapes), xiv

type (of entries of a shape), 19

type S, xv,54

type ir , xv

type , xv

type *, 54

variable, viii,19

variance, 19

$ , iv,xv,21,54

B , 60

S , 67

[,] , iv,21

[ ] , 62

n , 67

r , vii,xii

f , 55

+ , 19

, xiv,xv

, 54

I I , xii

*1 , 41

C-)0 , 41,42

(on arrows of ^ ), 71

«ABC (for shapes A,B,C) , 21

0. (for a shape A) , 21

(S^1

(for a shape A) , 21

VAB (for shapes A,B) , 21

&.R (for shapes A,B) , 21

£AB (for shapes A,B) , 21

^s (for a shape S) , 41-42

IT , xiii,xv

% , x

XQ , x

^oo i x

?Y

viii

T , xi