beta

Specifies the degree to which previous experiences (v-values) are considered in the decision function, in other words, how much weight is placed on the v-values in the decision function. A low value for beta means high exploration.

The value of the parameter beta is used in the decision function. See also mu.

The parameter beta can be either a single value, in which case the same weight is placed on all v-values, or specified per element-behavior pair. Wildcards (*) may be used to set several values at once.

Syntax

beta = e1->b1: v1, e1->b2: v2, ..., en->bn: vn, default: d
beta = v1
beta = *->*:v1  # Same as above
beta = e1->*:v1
beta = *->b1:v1

where v1,v2,...,vn and d are scalar expressions.

Description

beta = e1->b1: v1, e1->b2: v2, ..., en->bn: vn, default: d sets the individual weight on

  • v(e1->b1) to v1,

  • v(e1->b2) to v2, …,

  • v(en->bn) to v2,

and the weight for all other v-values to d.

  • The specification is independent of the list order:

    beta = e1->b1:v1, e1->b2:v2, default:d

    is the same as

    beta = e1->b2:v2, default:d, e1->b1:v1.

  • default need not be specified if all possible combinations element->behavior are present in the list. For example,

    stimulus_elements = e1, e2
behaviors = b1, b2
beta = e1->b1:v11, e1->b2:v12, e2->b1:v21, e2->b2:v22

beta = v1 sets the weight for all v-values to v1.

  • beta = v1 is the same as beta = default: v1.

Dependencies

  • The properties stimulus_elements and behaviors must be specified before beta.

  • Each stimulus element used in the specification of beta must be present in the parameter stimulus_elements.

  • Each behavior used in the specification of beta must be present in the parameter behaviors.

Examples

@variables x = 1
beta = element1->behavior1: x, element1->behavior2: x+1, default:x+2

sets the weight for v(element1->behavior1) to 1 and for v(element1->behavior1) to 2, and for the remaining possible element-behavior pairs to 3.

beta = element1->behavior1: 0.5, default:0

sets the weight for v(element1->behavior1) to 0.5, and for the remaining possible element-behavior pairs to 3.

beta = 0.1

sets the weight for all v-values to 0.1.